Which vitamin is associated with retinol, vision, bone growth, and immune function?

• A. Vitamin D
• B. Vitamin K
• C. Vitamin A
• D. Vitamin E

Answer: (C)

Vitamin A is the nutrient tied to retinol, vision, bone growth, and immune function. Retinol is the active form of vitamin A, and in the eye it helps regenerate a pigment called rhodopsin, which is essential for seeing in low light. Beyond vision, vitamin A supports healthy epithelial tissues and mucous membranes, which strengthens immune defenses. It also plays a role in bone growth and remodeling, though this works alongside other nutrients like vitamin D. The other vitamins have more specific primary roles: vitamin D is mainly about calcium absorption and bone mineralization, vitamin K is crucial for blood clotting, and vitamin E acts mainly as an antioxidant. So vitamin A best fits all the listed associations.