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
Korsakoff's psychosis is due to deficiency of: September 2003, March 2013 (b) 
Select and explain. 
A. Vitamin B1, B. Vitamin B2, C. Vitamin B3, D. Vitamin B12
A: Vitamin B1
Answer: A: Vitamin B1 
Explanation: Ans. A i.e. Vitamin B1