This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Gallbladder, Subject name: Surgery
[{'content': 'All of the following are causes of acalculous cholecystitis except: \nSelect and explain. \nA. Bile duct stricture, B. Schistosoma, C. Prolonged TPN, D. Major operations', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Causes of Acalculous Cholecystitis Elderly and critically ill patients after trauma Burns Longterm TPN Major operation (abdominal aneurysm repair and cardiopulmonary bypassQ) Diabetes mellitus', 'role': 'assistant'}]