This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Nutrition, Subject name: Pediatrics
The disease which is characterized by three D's-- diarrhea, dermatitis and dementia is due to deficiency of? 
Select and explain. 
A. Vitamin A, B. Niacin, C. Folate, D. Vitamin C
B: Niacin
Answer: B: Niacin 
Explanation: b. Niacin(Ref: Nelson's 20/c p 324, Ghai 8/e p 118)Diarrhea, Dermatitis & Dementia are seen in Pellagra, which is due to Niacin deficiency.