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': 'Most common cause of cholangitis - \nSelect and explain. \nA. Viral infection, B. CBD stone, C. Surgery, D. Amoebic infection', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Gall stones are the most common cause of obstruction in cholangitis.\n\nOther causes are\n\nbenign & malignant strictures\nparasites\ninstrumentation of the ducts and indwelling stents\npartially obstructed biliary enteric anastomosis\n\nMost common organisms cultured from bile in patients with cholongitis include\n\nEscherichia coli\nKlebsiella pneumoniae\nStreptococcus faecalis\nEnterobacter\nBacteroides fragilis', 'role': 'assistant'}]