Which fat-soluble vitamin can be synthesized by the skin upon exposure to ultraviolet B (UVB) radiation from sunlight?

• A. Vitamin K
• B. Vitamin A
• C. Vitamin E
• D. Vitamin D

Answer: (D)

Verified step by step guidance

1. Understand that fat-soluble vitamins include Vitamins A, D, E, and K, each with distinct roles and sources.
2. Recall that among these, only one vitamin can be synthesized by the skin when exposed to ultraviolet B (UVB) radiation from sunlight.
3. Recognize that Vitamin D is unique because it is produced in the skin through a chemical reaction involving 7-dehydrocholesterol and UVB rays.
4. Note that Vitamins A, E, and K are primarily obtained through dietary sources and are not synthesized by the skin.
5. Conclude that the fat-soluble vitamin synthesized by the skin upon UVB exposure is Vitamin D.