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: Medicine
[{'content': "Which of the following sites is responsible for the amnestic defect in Wernicke's Korsakoff syndrome: \nSelect and explain. \nA. Mamillary body, B. Thalamus, C. Periventricular Grey matter, D. Hippocampus", 'role': 'user'}, {'content': "Answer: B \nExplanation: Answer is B (Thalamus): The Amnestic effect in Wernicke's Korsakoff Syndrome is related to lesions in the dorso-medial nuclei of the thalamus. `Lesions in the dorsomedial nucleus of the thalamus seem to be the best correlate of the memory disturbance and confabulation' - Robbins", 'role': 'assistant'}]