Which vitamin is essential for vision and immune function?

• A. Vitamin C
• B. Vitamin D
• C. Vitamin A
• D. Vitamin B12

Answer: (C)

Vitamin A is essential for both vision and immune function due to its role in various biological processes. It is a critical component of rhodopsin, a pigment found in the retina that is necessary for low-light and color vision. Deficiency in vitamin A can lead to night blindness and other vision problems.

In addition to its importance in eyesight, vitamin A also plays a significant role in the immune system. It helps maintain the health of epithelial tissues, contributing to the body's first line of defense against pathogens. Vitamin A influences the production and function of white blood cells, which are vital for mounting an effective immune response.

While other vitamins like C and D do contribute to immune health, they do not have the same direct role in vision as vitamin A does. Vitamin B12 is primarily involved in metabolism and the formation of red blood cells, without significant direct contributions to either vision or immune function. Therefore, vitamin A is distinctly positioned as the essential nutrient for both vision and immune health.