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: Psychiatry
Korsakoff psychosis ? 
Select and explain. 
A. Thiamine deficiency, B. Folate deficiency, C. Niacin deficiency, D. Niacin deficiency
A: Thiamine deficiency
Answer: A: Thiamine deficiency 
Explanation: Ans. is 'a' i.e., Thiamine deficiency