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: Pathology
[{'content': 'In which of the following conditions " Onion Skin" fibrosis of bileduct is seen \nSelect and explain. \nA. Ulcerative collitis, B. Primary sclerosing cholangitis, C. Primary biliary cirrhosis, D. Cholangiocarcinoma', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Concentric periductal fibrosis is known as onion skin fibrosis and is classical of Primary sclerosing cholangitis.', 'role': 'assistant'}]