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': '"Onion skin" fibrosis of bile duct is seen in- \nSelect and explain. \nA. Primary biliary cirrhosis, B. Primary sclerosing cholangitis, C. Extrahepatic biliary fibrosis, D. Congenital hepatic fibrosis', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]