Niacin belongs to which vitamin category among the following?

• A. Vitamin A
• B. Vitamin B
• C. Vitamin C
• D. Vitamin D

Answer: (B)

Niacin is a B vitamin, specifically vitamin B3, and is part of the B-complex group of water-soluble vitamins that support energy metabolism. It functions as a coenzyme in redox reactions (NAD and NADP), helping the body convert carbohydrates, fats, and proteins into usable energy. Deficiency causes pellagra, a condition historically linked to nutrition problems. In contrast, vitamin A is fat-soluble and vital for vision and immunity, vitamin C is a separate water-soluble vitamin important for collagen synthesis and antioxidant protection, and vitamin D is fat-soluble and essential for calcium metabolism. So niacin clearly belongs to the vitamin B category.