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
[{'content': "Wernicke's encephalopathy involves which pa of CNS : \nSelect and explain. \nA. Mammillary body, B. Thalamus, C. Frontal lobe, D. Arcuate fasciculus", 'role': 'user'}, {'content': 'Answer: A \nExplanation: A i.e. Mammilary body', 'role': 'assistant'}]