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
Sclerosis of bile duct is seen in ? 
Select and explain. 
A. Primary sclerosing cholangitis, B. Obstructive jaundice, C. Bile duct atresia, D. Bile stones
A: Primary sclerosing cholangitis
Answer: A: Primary sclerosing cholangitis 
Explanation: Ans. is 'a' i.e., Primary sclerosing cholangitis