Which vitamin is synthesized in the skin through sunlight exposure?

The vitamin synthesized in the skin through sunlight exposure is Vitamin D. When the skin is exposed to ultraviolet B (UVB) rays from the sun, it triggers a chemical reaction that converts 7-dehydrocholesterol, a substance found in the skin, into Vitamin D3 (cholecalciferol). This form of Vitamin D is then converted into its active form, calcitriol, in the liver and kidneys, playing a crucial role in calcium metabolism and bone health.

The other vitamins listed do not undergo synthesis in the skin in response to sunlight. Vitamin A is primarily obtained through the diet from sources like carrots and leafy greens, while Vitamin C is a water-soluble vitamin that must be consumed, as our bodies cannot produce it. Vitamin E, also obtained from dietary sources, functions mainly as an antioxidant and does not involve sunlight in its synthesis. Thus, Vitamin D is unique among these options for its direct synthesis in the skin upon exposure to sunlight.