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': "Most common cause dementia in adult: \nSelect and explain. \nA. Alzheimer's, B. Multiinfarct, C. Pick' disease, D. Metabolic cause", 'role': 'user'}, {'content': "Answer: A \nExplanation: A i.e. Alzheimer's", 'role': 'assistant'}]