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 the risk factors for carcinoma gallbladder except: \nSelect and explain. \nA. Primary sclerosing cholangitis, B. Porcelain gallbladder, C. Multiple 2 cm gallstones, D. Choledochal cyst', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Risk Factors of Carcinoma Gallbladder Gallstones >3 cm Porcelain gallbladder Anomalous pancreatobiliary junction Choledochal cysts Adenomatous polyps Primary sclerosing cholangitis Obesity Salmonella typhi infection', 'role': 'assistant'}]