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: Medicine
[{'content': 'All of the following are known predesposing factors for cholangiocarcinoma except : \nSelect and explain. \nA. CBD stones, B. Clonorchis sinensis, C. Ulcerative colitis, D. Primary sclerosing cholangitis', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Answer is A (CBD stone) : Cholelithiasis is not clearly a predisposing factor for Cholangiocarcinoma - Harrison The predisposing factors of cholangiocarcinoma include : I. Chronic hepato-biliary parasite infection (Clonorchiasis or Asiatic cholangio-hepatitis) Q Congenital Anomaly with ectatic ducts (Choledochal cyst).Q Sclerosing cholangitis Q Ulcerative colitis Occupational exposure to carcinogensQ(Rubber + Automotive plants) Note: Nodular lesions that arise at the bifitrcation of hepatic ducts are called Klastskin tumors. Q', 'role': 'assistant'}]