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': 'Risk factor for cholangiocarcinoma all except: \nSelect and explain. \nA. Chronic typhoid carrier, B. Chronic ulcerative colitis, C. Parasitic infestation, D. Choledocholithiasis', 'role': 'user'}, {'content': "Answer: D \nExplanation: Choledocholithiasis Risk factors for Choangiocarcinoma - Primary sclerosing cholangitis - Choledochal cyst - Ulcerative colitis - Clonorchis sinensis - Chronic typhoid carriers * Other risk factors - Hepatolithiasis - Biliary enteric anastomosis - Liver flukes - Dietary nitrosamines - Exposure to thorotrast, dioxin Mnemonic 5 C's", 'role': 'assistant'}]