This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
[{'content': 'Pellagra is caused by deficiency of which vitamin \nSelect and explain. \nA. B2, B. B3, C. B1, D. Folic acid', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]