Which vitamin is synthesized in human skin upon exposure to sunlight?
A
Vitamin D
B
Vitamin C
C
Vitamin B12
D
Vitamin A
Correct Answer: Option A — Vitamin D
Explanation:
Vitamin D is synthesized in the skin when it is exposed to ultraviolet B (UVB) radiation from sunlight, triggering a chemical reaction that converts a cholesterol derivative into active vitamin D.