Which vitamin is produced in human skin in the presence of sunlight?

(A) Vitamin A
(B) Vitamin B
(C) Vitamin C
(D) Vitamin D

The answer is: (D) Vitamin D
The vitamin produced in human skin in the presence of sunlight is vitamin D.
When exposed to sunlight, a cholesterol-based compound in the skin called 7-dehydrocholesterol is converted into previtamin D3. This previtamin D3 then spontaneously transforms into vitamin D3, which is the form that is transported to the liver and kidneys to be converted into its active hormonal form.