What vitamin is produced when the skin is exposed to sunlight?

When the skin is exposed to sunlight, specifically ultraviolet B (UVB) rays, it synthesizes Vitamin D. This process occurs when the UVB rays convert 7-dehydrocholesterol, a compound present in the skin, into Vitamin D3 (cholecalciferol). Vitamin D plays a crucial role in various bodily functions, including promoting calcium absorption, supporting bone health, and maintaining immune system function.

The other options presented do not involve synthesis through sunlight exposure. Vitamin A is obtained primarily from dietary sources and is important for vision and immune function. Vitamin B12 is also obtained mainly from food and is essential for the production of red blood cells and neurological function. Vitamin C is another dietary nutrient, well known for its role in skin health and immune support, but it is not produced in the body via sunlight exposure. Therefore, the correct answer, Vitamin D, stands out as the one specifically produced through the interaction of sunlight with the skin.