Which vitamin is characterized by its ability to be synthesized in the skin upon exposure to sunlight?

A Vitamin A
B Vitamin D ✓
C Vitamin E
D Vitamin K

Explanation

Vitamin D is unique among vitamins because it can be synthesized in the skin from cholesterol upon exposure to ultraviolet B (UVB) rays from the sun.

Source

Harvard School of Public Health
Vitamins Nutrition Vitamin Synthesis Medium MEDICAL Confidence: high