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: Pathology
[{'content': "Wernick's encephalopathy is caused by deficiency of \nSelect and explain. \nA. Thiamine, B. Cyanocohalamine, C. Niacin, D. Riboflavin", 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]