Name one key function of vitamin A.

Vitamin A plays a crucial role in several bodily functions, with one of its key contributions being in the area of vision and immune function. In the context of vision, vitamin A is essential for the formation of rhodopsin, a pigment found in the retina that is necessary for low-light and color vision. Without adequate vitamin A, individuals can experience night blindness and other vision-related issues.

Additionally, vitamin A is vital for maintaining the integrity of epithelial tissues, including those in the eyes and the immune system. It helps to regulate the immune response by supporting the activity of T cells and other immune cells, thereby enhancing the body’s ability to fight off infections. This connection to both eyesight and immune health underscores the multifaceted role that vitamin A plays in overall bodily function.

The other options pertain to functions that are not directly associated with vitamin A. For example, muscle development is primarily influenced by protein and other nutrients, while calcium absorption is mainly regulated by vitamin D. Cognitive function is more closely linked to a variety of nutrients, including certain B vitamins and omega-3 fatty acids, rather than vitamin A alone.