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
"Onion skin" fibrosis of bile duct is seen in- 
Select and explain. 
A. Primary biliary cirrhosis, B. Primary sclerosing cholangitis, C. Extrahepatic biliary fibrosis, D. Congenital hepatic fibrosis
B: Primary sclerosing cholangitis
Answer: B: Primary sclerosing cholangitis 
Explanation: None