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: Surgery
[{'content': "True about Ogilive's syndrome are all except: \nSelect and explain. \nA. It is caused by mechanical obstruction of the colon, B. It involves entire / part of the large colon, C. It occurs after previous surgery, D. It occurs commonly after narcotic use", 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]