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: Social & Preventive Medicine
[{'content': "Korsakoff's psychosis is due to deficiency of: September 2003, March 2013 (b) \nSelect and explain. \nA. Vitamin B1, B. Vitamin B2, C. Vitamin B3, D. Vitamin B12", 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. A i.e. Vitamin B1', 'role': 'assistant'}]