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': 'All of the following are risk factors for carcinoma gall bladder, EXCEPT - \nSelect and explain. \nA. Typhoid carriers, B. Adenomatous gall bladder polyps, C. Choledochal cysts, D. Oral contraceptives', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]