Which vitamin is produced in the body when exposed to the sun?

When the skin is exposed to sunlight, specifically ultraviolet B (UVB) radiation, it synthesizes vitamin D. This process begins when UVB rays convert a precursor molecule in the skin, 7-dehydrocholesterol, into vitamin D3, also known as cholecalciferol. Vitamin D is essential for several bodily functions, primarily in regulating calcium and phosphorus levels, which are crucial for bone health. Moreover, vitamin D plays a role in immune function and has been linked to mood regulation and overall well-being.

In contrast, the other vitamins listed are not synthesized in the body through exposure to sunlight. Vitamin C is primarily obtained through dietary sources, such as fruits and vegetables. Vitamin A can also be acquired from dietary sources and does not involve sunlight for its production. Vitamin E, known for its antioxidant properties, is predominantly sourced from the diet. Thus, the unique ability of the skin to produce vitamin D when exposed to the sun makes it the correct answer.