This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: vitamins, Subject name: Biochemistry
[{'content': 'Niacin deficiency causes \nSelect and explain. \nA. Pigmentation, B. Diarrhea, C. Rash, D. Lactic acidosis', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Deficiency of niacin: A deficiency of niacin causes pellagra, a disease involving the skin, gastrointestinal tract, and CNS. The symptoms of pellagra progress through the three Ds: dermatitis, diarrhoea, dementia--and, if untreated, death. Reference: Lippincott Textbook of Biochemistry pg no. 380', 'role': 'assistant'}]