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: Surgery
[{'content': 'Causes of bile duct strictures are:a) Bile duct carcinomab) Chronic pancreatitisc) Acute pancreatitisd) Traumae) CBD stone \nSelect and explain. \nA. abcd, B. bcde, C. abde, D. ade', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]