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': 'The most common postoperative psychiatric condition is: \nSelect and explain. \nA. Schizophrenia, B. Delirium, C. Chronic brain syndrome, D. Depression', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Delirium', 'role': 'assistant'}]