Which vitamin is primarily produced when skin is exposed to sunlight?

The production of vitamin D in the skin is triggered by exposure to ultraviolet (UV) rays from sunlight. When the skin is exposed to these rays, specifically UVB rays, a chemical reaction occurs that converts 7-dehydrocholesterol, a compound present in the skin, into previtamin D3. This subsequently transforms into vitamin D3 (cholecalciferol), which is then converted into active vitamin D (calcitriol) within the body.

Vitamin D plays a crucial role in regulating calcium and phosphorus in the body, which are essential for maintaining healthy bones and teeth. It also supports immune function and has been linked to various health benefits.

The other vitamins listed—C, A, and E—do not undergo synthesis in the skin through sunlight exposure. Vitamin C is primarily obtained through dietary sources and functions as an antioxidant. Vitamin A is obtained through dietary sources as well and is important for vision and immune function. Vitamin E, another antioxidant, is also obtained mainly from the diet and plays a role in protecting cells from oxidative damage. Thus, among the choices given, vitamin D is the only one that is synthesized in the skin when exposed to sunlight.