This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: G.I.T, Subject name: Pathology
[{'content': 'Which is risk factor for cholangiocarcinoma \nSelect and explain. \nA. Obesity, B. Primary sclerosing cholangitis, C. Salmonella carrier state, D. HBV infection', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Risk factors include primary sclerosing cholangitis Congenital fibropolycystic disease of biliary tree Infestation by Clonorchis sinensis or Opisthorchis viverrini HCV infection Exposure to Thorotrast TEXT BOOK OF ROBBINS BASIC PATHOLOGY NINTH EDITION PAGE.643', 'role': 'assistant'}]