Concept: Carrier proteins undergo conformational change to transport specific solutes across the cell membrane by both passive transport (facilitated diffusion) and active transport.

Solution: Carrier Proteins (Option B) are membrane transport proteins that facilitate both active transport (e.g., Na⁺/K⁺-ATPase pump) and passive transport (facilitated diffusion, e.g., GLUT glucose transporters). In contrast, pores or channel proteins only mediate passive diffusion along electrochemical gradients and cannot perform active transport.