#1 of 32
SZABMU 2024
Permalink
If a person becomes ill with HIV and survives, then the type of immunity developed is:
A
Artificial passive immunity
B
Natural passive immunity
C
Artificial active immunity
D
Natural active immunity
View Answer & Propolis Autopsy
Correct Key: Option D
Diagnostic Explanation
Concept:Immunity categorized by how the antigen is encountered (natural vs syringe) and who does the immune work (host vs donor).
Formula:None
Solution:- The person caught the HIV virus through biological, real-world transmission. This makes the exposure natural.
- The person became ill, meaning their own immune system fought the virus and (theoretically in this prompt) survived by creating their own antibodies and cytotoxic T-cells. This makes it an active metabolic process.
- Therefore, the resulting memory represents natural active immunity.
Why other options are incorrect:- Artificial immunity implies medical intervention (vaccine or antivenom). Passive implies receiving someone else's antibodies.
#2 of 32
SZABMU 2024
Permalink
Which of the following chemicals is responsible for causing inflammation in upper respiratory tract?
View Answer & Propolis Autopsy
Correct Key: Option C
Diagnostic Explanation
Concept:Allergic and inflammatory responses in mucosal tissues are driven by mast cell degranulation.
Formula:None
Solution:- When allergens (like pollen) enter the upper respiratory tract, they bind to IgE antibodies on local mast cells.
- This triggers the massive release of histamine.
- Histamine binds to local H1 receptors, causing aggressive vasodilation and mucus hypersecretion, resulting in the classic inflammatory symptoms of a runny nose and congestion.
Why other options are incorrect:- Ampicillin: An antibiotic.
- Nicotine: A stimulant found in tobacco.
- Acetyl amine: Not a primary physiological inflammatory mediator.
#3 of 32
NUMS 2024
Permalink
During COVID-19 epidemic the plasma of recovered patients was injected in COVID patients. This proved quite effective, which component of plasma do you think was responsible for this?
View Answer & Propolis Autopsy
Correct Key: Option C
Diagnostic Explanation
Concept:Convalescent plasma therapy relies on the principle of artificially acquired passive immunity.
Formula:None
Solution:- When a patient successfully recovers from a virus like COVID-19, their blood plasma is flooded with highly specific neutralizing antibodies (IgG) against the SARS-CoV-2 spike protein.
- By extracting this plasma and transfusing it into a currently sick patient, the sick patient receives immediate, pre-made immune weapons.
- These antibodies rapidly bind to and neutralize the virus in the new host, aiding their recovery.
Why other options are incorrect:- While plasma contains traces of interferons and interleukins, these degrade quickly. The stable, highly specific, and massively abundant therapeutic agents are the antibodies.
#4 of 32
NUMS 2024
Permalink
Choose the one which is an example of artificial active immunity:
A
Foetus receiving antibodies of mother through placenta
B
Mother receiving antibodies
C
Babies receiving MMR shorts
D
Prevention of disease due to previous infection
View Answer & Propolis Autopsy
Correct Key: Option C
Diagnostic Explanation
Concept:Artificial active immunity involves the medical administration of an antigen to stimulate a permanent immune response.
Formula:None
Solution:- Artificial: The immune system is stimulated via a clinical injection (a shot/vaccine), rather than a natural environmental encounter.
- Active: The MMR (Measles, Mumps, Rubella) vaccine contains attenuated viruses. The baby's immune system must actively process these and generate its own memory cells.
- Therefore, babies receiving MMR shots is the perfect example of artificial active immunity.
Why other options are incorrect:- Foetus receiving antibodies: Natural passive immunity.
- Previous infection: Natural active immunity.
#5 of 32
NUMS 2024
Permalink
Which of the following type of T-cells are required for the activation of B-cells?
View Answer & Propolis Autopsy
Correct Key: Option A
Diagnostic Explanation
Concept:The adaptive immune system requires a "two-key" system to prevent accidental autoimmune activation; B-cells usually cannot mount a full response alone.
Formula:None
Solution:- When a naive B-cell encounters its specific antigen, it engulfs it and displays pieces of it on its surface via MHC-II molecules.
- However, to undergo rapid clonal expansion and become plasma cells, the B-cell requires chemical permission (interleukins).
- This permission is granted by Helper T-cells (CD4+ cells) that recognize the displayed antigen and bind to the B-cell, officially activating it.
Why other options are incorrect:- Cytotoxic T-cells: Kill infected cells directly.
- Suppressor T-cells: Turn off the immune response to prevent tissue damage.
#6 of 32
SZABMU 2024 Reconduct
Permalink
Immunity provided to baby through colostrum is an example of:
A
Natural active immunity
B
Artificial active immunity
C
Natural passive immunity
D
Artificial passive immunity
View Answer & Propolis Autopsy
Correct Key: Option C
Diagnostic Explanation
Concept:Maternal antibody transfer is an evolutionary mechanism to protect neonates before their own immune system fully boots up.
Formula:None
Solution:- Colostrum, the first breast milk produced, is incredibly rich in secretory IgA antibodies.
- Because breastfeeding is a standard biological process, the transfer is natural.
- Because the baby is merely absorbing these pre-made antibodies without utilizing its own immune machinery to create them, the immunity is passive.
Why other options are incorrect:- Active immunity would require the baby to be infected with a disease or injected with a vaccine.
#7 of 32
SZABMU 2023
Permalink
Which may NOT be a possible action of interferons?
B
Activate natural killer cells
View Answer & Propolis Autopsy
Correct Key: Option D
Diagnostic Explanation
Concept:Interferons are signaling proteins (cytokines) released by host cells in response to the presence of pathogens, particularly viruses.
Formula:None
Solution:- Interferons act as distress signals. They belong to the cytokine family (A is true).
- They actively "interfere" with viral replication and activate other immune cells (C is true), including Natural Killer (NK) cells and macrophages (B is true).
- However, interferons themselves are just protein molecules; they are not living cells, and therefore they do not have the cellular machinery to secrete interleukins. Cells secrete cytokines, not the other way around.
Why other options are incorrect:- Options A, B, and C describe valid properties or downstream effects of interferons.
#8 of 32
ETEA 2023
Permalink
The immune cells that clean up pus as a part of the healing process is:
View Answer & Propolis Autopsy
Correct Key: Option B
Diagnostic Explanation
Concept:Pus consists of dead pathogens, tissue debris, and millions of dead neutrophils that fought the initial infection.
Formula:None
Solution:- While neutrophils are the first responders and form the bulk of pus when they die, they do not clean it up.
- Macrophages are large, long-lived phagocytes that arrive later at the infection site.
- They act as the "garbage collectors" of the immune system, engulfing and digesting the dead neutrophils, debris, and remaining bacteria to facilitate tissue healing.
Why other options are incorrect:- Neutrophils: Their death creates the pus.
- Antibodies: Molecules, not cells; they cannot phagocytose debris.
#9 of 32
NUMS 2023
Permalink
Which may not be a mode of action of an antibody:
A
Neutralizing an antigen
B
Precipitating an antigen
View Answer & Propolis Autopsy
Correct Key: Option C
Diagnostic Explanation
Concept:Antibodies are highly specialized Y-shaped proteins, not living cells, meaning they operate strictly through chemical binding mechanics.
Formula:None
Solution:- Antibodies bind to antigens to neutralize them (blocking viral entry), precipitate them (clumping soluble antigens), and opsonize them (enhancing phagocytosis by macrophages).
- However, secretion of cytokines requires a living cell with a nucleus, ribosomes, and a Golgi apparatus (like a T-cell or Macrophage).
- An antibody is merely a secreted protein molecule and has no biological machinery to secrete anything itself.
Why other options are incorrect:- Neutralization, precipitation, and opsonization are the three classic textbook mechanisms of antibody action.
#10 of 32
NUMS 2023
Permalink
Vaccination is an example of:
A
Natural passive immunity
B
Natural active immunity
C
Acquired/artificial active immunity
D
Acquired/artificial passive immunity
View Answer & Propolis Autopsy
Correct Key: Option C
Diagnostic Explanation
Concept:Medical interventions that train the immune system utilize artificial means to generate an active biological response.
Formula:None
Solution:- A vaccine consists of medical (artificial) injection of an antigen.
- This forces the patient's own immune system to expend energy to synthesize antibodies and form memory cells (an active process).
- Therefore, vaccination is classified as artificial active immunity.
Why other options are incorrect:- Natural active: Surviving a naturally caught disease.
- Artificial passive: Being injected with someone else's pre-made antibodies (antivenom).
#11 of 32
ETEA 2023 Retake
Permalink
All of these following are true about neutrophils except:
A
Most abundant form of WBCs
C
Made by the thymus gland
D
Released by the bone marrow
View Answer & Propolis Autopsy
Correct Key: Option C
Diagnostic Explanation
Concept:Neutrophils are the highly abundant, rapid-response phagocytes of the innate immune system.
Formula:None
Solution:- Neutrophils make up \(60\text{-}70\%\) of all circulating white blood cells (most abundant).
- They are produced and released by the red bone marrow.
- They have a very short lifespan, surviving only a few days before dying to form pus.
- They are NOT made by the thymus gland. The thymus is strictly dedicated to the maturation of T-lymphocytes.
Why other options are incorrect:- Options A, B, and D are factually correct statements regarding neutrophil physiology.
#12 of 32
UHS 2022
Permalink
____ proteins are produced by WBCs in response to ____ and provide immunity.
View Answer & Propolis Autopsy
Correct Key: Option D
Diagnostic Explanation
Concept:The humoral immune response is a direct reaction to foreign molecular markers.
Formula:None
Solution:- When White Blood Cells (specifically B-lymphocytes) detect a foreign shape (an antigen), they differentiate into plasma cells.
- These plasma cells synthesize and release highly specific antibodies (immunoglobulins).
- These antibodies bind to the antigens to neutralize them, thus providing immunity.
Why other options are incorrect:- WBCs do not produce antibiotics (fungi and bacteria produce antibiotics).
- Antibodies are not produced in response to healthy RBCs (unless it is a mismatched blood transfusion).
#13 of 32
SZABMU 2022
Permalink
Which of the following helps in developing immunity against germs?
View Answer & Propolis Autopsy
Correct Key: Option C
Diagnostic Explanation
Concept:Long-term immunity requires the generation of memory lymphocytes.
Formula:None
Solution:- Vaccination deliberately exposes the immune system to weakened antigens.
- This safely triggers the primary immune response, resulting in the creation of memory B and memory T cells.
- If the real germ ever enters the body, these memory cells mount an overwhelmingly fast secondary response, preventing illness.
Why other options are incorrect:- Antibiotics: Kill existing bacteria but do not train the immune system to remember them.
- Radio/Chemotherapy: Cytotoxic treatments that actually destroy rapidly dividing cells, severely weakening the immune system.
#14 of 32
NUMS 2020
Permalink
The cells which play very important role in developing immunity are:
View Answer & Propolis Autopsy
Correct Key: Option B
Diagnostic Explanation
1. Concept:The immune system relies on specialized white blood cells to mediate innate and adaptive defenses. Long-term specific immunity (humoral and cell-mediated immunity) is orchestrated by lymphocytes (B-cells and T-cells).
2. High-Yield PYQ Note:This question is a high-yield medical entrance staple that appeared in both
PMC-2020 and
NUMS-2023.
3. Solution:- Lymphocytes: Key effectors of adaptive immunity. B-lymphocytes synthesize antibodies (humoral defense), while T-lymphocytes govern cell-mediated cytotoxicity and immune coordination.
4. Why other options are incorrect:- Monocytes: Phagocytic agranulocytes that mature into tissue macrophages; part of the innate first/second line of defense.
- Neutrophils: Short-lived granulocytic phagocytes active in acute bacterial infection.
- Thrombocytes: Platelets involved in hemostasis and blood clotting, not developing specific immunity.
#15 of 32
SZABMU 2020
Permalink
Antibodies are manufactured in:
View Answer & Propolis Autopsy
Correct Key: Option D
Diagnostic Explanation
1. Concept:Humoral immunity involves the synthesis and secretion of specific immunoglobulins (antibodies) to neutralize pathogens and toxins in body fluids.
2. High-Yield PYQ Note:This core concept was tested in both
PMC-2020 and
SZABMU-2024 (Reconduct).
3. Solution:- B lymphocytes: Upon antigen presentation and activation (facilitated by Helper T-cells), B-lymphocytes differentiate into plasma cells that produce and secrete large volumes of antigen-specific antibodies.
4. Why other options are incorrect:- T lymphocytes: Mediate cell-mediated immunity and provide cytokines; they do not synthesize or secrete soluble antibodies.
- Red blood cells (Erythrocytes): Specialized for oxygen and carbon dioxide transport via hemoglobin.
- Platelets (Thrombocytes): Non-nucleated fragments specialized in blood coagulation.
#16 of 32
PMC 2020
Permalink
Autoimmune diseases act at the principle of:
View Answer & Propolis Autopsy
Correct Key: Option B
Diagnostic Explanation
Concept:A healthy immune system exhibits "self-tolerance," meaning it ignores the body's own tissues while attacking foreign antigens.
Formula:None
Solution:- In an autoimmune disease, there is a breakdown in immunological tolerance.
- The body's T-cells and auto-antibodies mistakenly identify the host's own healthy cells as foreign invaders.
- This results in the immune system actively destroying its own tissues, fundamentally operating on the principle of self against self.
Why other options are incorrect:- "Self against antigens" is the normal, healthy immune response.
#17 of 32
MDCAT 2019
Permalink
Now a day, every new born gets regular shots of vaccine for polio. It contains ____ for polio to make a child immune against this disease.
View Answer & Propolis Autopsy
Correct Key: Option D
Diagnostic Explanation
Concept:The fundamental mechanism of a vaccine is to expose the immune system to a safe version of a pathogen.
Formula:None
Solution:- A vaccine contains attenuated (weakened) or dead pathogens, or pieces of the pathogen's surface proteins.
- These immune-provoking components are known as antigens.
- When injected, the body recognizes these antigens as foreign and mounts an active immune response to create memory cells.
Why other options are incorrect:- Antibodies/Antisera: Used for immediate, temporary passive immunity (like antivenom), not long-term vaccination.
- Antibiotics: Chemicals that kill bacteria, completely useless against a virus like polio.
#18 of 32
MDCAT 2019
Permalink
A person got an infection, he became ill but then he survived. What do you think which type of immunity he would have developed?
A
Naturally induced active immunity
C
Artificially induced active immunity
View Answer & Propolis Autopsy
Correct Key: Option A
Diagnostic Explanation
Concept:Immunity acquired through real-world exposure to a pathogen stimulates the body's natural defense mechanisms.
Formula:None
Solution:- Because the person caught the disease through natural environmental exposure (not a syringe), the trigger is naturally induced.
- Because the person's own immune system successfully fought off the infection and generated memory B and T cells, the immunity is active.
- This results in highly effective, naturally induced active immunity.
Why other options are incorrect:- Artificially induced: This would imply they received a vaccine.
- Passive immunity: Implies they were given a cure of pre-made antibodies.
#19 of 32
AJK 2019
Permalink
The prevention of disease by artificial activation of immune response is possible by:
View Answer & Propolis Autopsy
Correct Key: Option C
Diagnostic Explanation
Concept:Artificial, active immunization relies on medical science to prepare the immune system prior to an actual infection.
Formula:None
Solution:- The process of artificially forcing the body to actively mount an immune response and generate memory cells is achieved using vaccines.
- Vaccines contain weakened antigens that train the immune system without causing the actual disease.
Why other options are incorrect:- Antibodies: Provide artificial passive immunity, not an active response.
- Drugs: Manage symptoms or kill pathogens directly but do not activate immunological memory.
#20 of 32
AJK 2019
Permalink
Is a foreign substance, which stimulates the formation of antibodies?
View Answer & Propolis Autopsy
Correct Key: Option B
Diagnostic Explanation
Concept:The immune system utilizes molecular markers to distinguish "self" from "non-self".
Formula:None
Solution:- Any substance (usually a protein or polysaccharide) that the immune system recognizes as foreign is called an antigen.
- The presence of an antigen binds to specific receptors on B-cells and T-cells, stimulating an immune cascade that results in the formation of targeted antibodies.
Why other options are incorrect:- Antibiotic: A drug used to kill bacteria.
- Transposon: A jumping gene sequence in DNA.
#21 of 32
MDCAT 2018
Permalink
Cell mediated immune response is given by:
View Answer & Propolis Autopsy
Correct Key: Option C
Diagnostic Explanation
Concept:The adaptive immune system delegates responsibilities between two main classes of lymphocytes.
Formula:None
Solution:- While B lymphocytes handle the humoral (antibody) response, T lymphocytes handle the cell-mediated response.
- Cytotoxic T cells physically dock with infected host cells and release perforin and granzymes to induce apoptosis.
Why other options are incorrect:- Neutrophils/Macrophages: Part of the innate, non-specific immune system (phagocytosis).
- B lymphocytes: Responsible for humoral immunity.
#22 of 32
MDCAT 2018
Permalink
Anti-venom given after a snake bite venom is an example of:
A
Artificial active immunity
B
Artificial passive immunity
C
Natural active immunity
D
Natural passive immunity
View Answer & Propolis Autopsy
Correct Key: Option B
Diagnostic Explanation
Concept:Snake bites require immediate neutralization of the toxin, which is too fast for the victim's immune system to mount an active response.
Formula:None
Solution:- Anti-venom consists of concentrated antibodies harvested from an animal (like a horse) that has been hyperimmunized against the venom.
- Since the antibodies are injected via syringe, it is an artificial transfer.
- Because the victim's body is receiving pre-formed defenses rather than making its own, it is passive immunity.
Why other options are incorrect:- Active immunity would mean waiting weeks for the victim to produce their own antibodies, by which point the venom would have been fatal.
#23 of 32
MDCAT 2017
Permalink
____ cells survive for a few days and secrete a huge number of antibodies in blood, tissue fluids or lymph.
View Answer & Propolis Autopsy
Correct Key: Option D
Diagnostic Explanation
Concept:Following activation by an antigen, naive B-cells undergo rapid clonal expansion and differentiation.
Formula:None
Solution:- An activated B-cell differentiates into an effector cell called a plasma cell (or plasma clone).
- These plasma cells become highly metabolic factories, surviving only for a few days to weeks, but secreting up to 2,000 antibody molecules per second into the circulation.
Why other options are incorrect:- Memory cells: Survive for decades to provide long-term immunity but do not secrete large volumes of antibodies themselves until reactivated.
#24 of 32
MDCAT 2017
Permalink
Vaccination is:
A
Natural active immunity
B
Artificial active immunity
C
Natural passive immunity
D
Artificial passive immunity
View Answer & Propolis Autopsy
Correct Key: Option B
Diagnostic Explanation
Concept:Vaccines simulate an infection to trick the immune system into developing immunological memory.
Formula:None
Solution:- Because a vaccine is deliberately and medically introduced into the body, it is an artificial process.
- Because the vaccine contains antigens that force the host's own immune system to actively generate antibodies and memory cells, it provides active immunity.
- Therefore, vaccination equals artificial active immunity.
Why other options are incorrect:- Natural active: Getting sick from the wild pathogen.
- Artificial passive: Receiving an injection of pre-made antivenom.
#25 of 32
MDCAT 2016
Permalink
The type of immunity in which antibodies are passed from one individual to another is called:
B
Natural Active Immunity
C
Artificial Active Immunity
View Answer & Propolis Autopsy
Correct Key: Option A
Diagnostic Explanation
Concept:The direct transfer of immune components bypasses the need for the recipient to undergo a primary immune response.
Formula:None
Solution:- If a person receives pre-made antibodies (either artificially via injection or naturally via breast milk/placenta), their immune system did not "actively" create them.
- Because the recipient is entirely passive in the acquisition of these defenses, it is termed Passive Immunity.
Why other options are incorrect:- Active Immunity: Always requires the host to be exposed to the antigen and expend energy manufacturing their own antibodies and memory cells.
#26 of 32
NTS 2015
Permalink
In ____ response, B-cells produce plasma cells that synthesize antibodies and release in blood plasma and tissue fluid.
View Answer & Propolis Autopsy
Correct Key: Option B
Diagnostic Explanation
Concept:The branch of adaptive immunity governed by B-lymphocytes operates via fluid-borne macromolecules.
Formula:None
Solution:- Historically, bodily fluids were called "humors".
- Because antibodies are secreted into the blood plasma and lymph (extracellular fluids) to combat circulating pathogens, the B-cell driven immune pathway is called the Humoral response.
Why other options are incorrect:- Cell-Mediated: Controlled by T-cells targeting intracellular pathogens.
- Hormonal: Relates to the endocrine system, not immunity.
#27 of 32
MDCAT 2015
Permalink
Response of body against the transplanted organ is:
View Answer & Propolis Autopsy
Correct Key: Option D
Diagnostic Explanation
Concept:Tissue rejection is primarily a function of the cellular branch of the adaptive immune system recognizing foreign MHC markers.
Formula:None
Solution:- A transplanted organ contains cells with non-self Major Histocompatibility Complex (MHC) or HLA antigens.
- Cytotoxic T-cells identify these foreign cells and directly induce apoptosis (cell death) in the transplanted tissue.
- This direct cellular attack classifies graft rejection strictly as a cell-mediated response.
Why other options are incorrect:- Antibodies (humoral response) play a minor or hyperacute role, but the primary chronic rejection is T-cell mediated.
#28 of 32
MDCAT 2014
Permalink
Which part of antibody recognizes the antigen during immune response?
View Answer & Propolis Autopsy
Correct Key: Option D
Diagnostic Explanation
Concept:Antibodies (immunoglobulins) have a highly specific lock-and-key mechanism to bind to countless diverse antigens.
Formula:None
Solution:- An antibody is a Y-shaped molecule. The tips of the "Y" form the antigen-binding site.
- This specific region is composed of the variable parts (variable regions) of both the heavy and light chains.
- Its unique amino acid sequence allows it to recognize and bind tightly to one specific antigen epitope.
Why other options are incorrect:- Constant part: Determines the mechanism of action/class of the antibody (e.g., IgG, IgE), but plays no role in specific antigen recognition.
#29 of 32
MDCAT 2014
Permalink
Which one of the following glands is involved in the production of lymphocytes?
View Answer & Propolis Autopsy
Correct Key: Option B
Diagnostic Explanation
Concept:Primary lymphoid organs provide the necessary microenvironment for the maturation and selection of lymphocytes.
Formula:None
Solution:- While all lymphocytes originate in the bone marrow, T-lymphocytes migrate to the thymus gland to mature.
- The thymus provides hormones (thymosins) and a selective environment where T-cells become immunocompetent and learn self-tolerance.
Why other options are incorrect:- Pineal, Pituitary, and Adrenal glands are purely endocrine organs that secrete hormones regulating sleep, metabolism, and stress, completely unrelated to lymphocyte production.
#30 of 32
MDCAT 2014
Permalink
Antibodies are proteins and made up of how many polypeptide chains?
View Answer & Propolis Autopsy
Correct Key: Option D
Diagnostic Explanation
Concept:Immunoglobulins are large, complex glycoproteins characterized by a standardized, multi-chain quaternary structure.
Formula:None
Solution:- A standard monomeric antibody (like IgG) is composed of exactly four polypeptide chains.
- These include two identical longer chains (Heavy chains) and two identical shorter chains (Light chains).
- They are held together in a Y-shape by disulfide bridges.
Why other options are incorrect:- Antibodies are not simple single or dimeric chains; the fundamental unit universally requires four polypeptides to form the binding sites correctly.
#31 of 32
MDCAT 2014
Permalink
T-lymphocytes recognize antigen and attack microorganisms or transplanted organ and tissues. This effect is called:
C
Humoral immune response
View Answer & Propolis Autopsy
Correct Key: Option A
Diagnostic Explanation
Concept:The adaptive immune system is divided into two broad branches based on the effector mechanism: humoral (antibodies) and cell-mediated (cells).
Formula:None
Solution:- T-lymphocytes (specifically Cytotoxic T-cells) directly engage and destroy infected host cells, cancer cells, or foreign transplant cells.
- Because this destruction is carried out directly by physical cell-to-cell contact rather than by secreted molecules, it is termed a cell-mediated response.
Why other options are incorrect:- Humoral response: Driven by B-cells and the antibodies they secrete into the body's humors (fluids).
#32 of 32
MDCAT 2014
Permalink
What type of immunity is achieved by injecting antibodies, antiserum, anti-venom serum?
B
Artificially induced immunity
D
Naturally induced immunity
View Answer & Propolis Autopsy
Correct Key: Option C
Diagnostic Explanation
Concept:Immunity can be categorized by how it is acquired (natural vs. artificial) and whether the host makes their own response (active vs. passive).
Formula:None
Solution:- When pre-formed antibodies (like antivenom or antiserum) are injected into a patient, the patient's immune system does not do the work of creating them.
- Because the body is passively receiving external defense molecules, this is defined as passive immunity (specifically, artificial passive immunity).
- This provides immediate, but short-lived, protection.
Why other options are incorrect:- Active immunity: Occurs when the host's own B and T cells generate a response (e.g., getting a vaccine or catching a disease).
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