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': 'Stone formation in Gall bladder is enhanced by all except : \nSelect and explain. \nA. Clofibrate therapy, B. Ileal resection, C. Cholestyramine therapy, D. Vagal stimulation', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Answer is D (Vagal stimulation) Stone formation is enhanced by Truncal vagotomy (not by vagal stimulation).', 'role': 'assistant'}]