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': '60 yrs old, air in biliary tree, colicky abdominal pain hyper-peristaltic abdominal sounds diagnosis - \nSelect and explain. \nA. Gall stone ileus, B. Hemobilia, C. Cholangitis, D. Pneumobilia', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Answer- A. Gall stone ileusPresence in air in biliary tract along with sign of intestinal obstruction is characteristic of gall stone ileus.', 'role': 'assistant'}]