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: Unknown
[{'content': 'Abdominal aortic aneurysm is operated when the size is more than: \nSelect and explain. \nA. 35 mm, B. 45 mm, C. 55 mm, D. 65 mm', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ref. Sabiston Textbook of Surgery. Pg. 1723\n\xa0\nINDICATIONS FOR OPERATION\nAsymptomatic –\n\nAneursym\xa0 >55mm in anteroposterior diameter.\nPatient fit for surgery (expected mortality rate <5%)\nIndications for endoluminal operation are the same as for open operation .\n\nSymptomatic .\n\nAneursym of any size that is painful or tender\nAneursym of any size that is causing distal embolisation .\nIndications are wider than for an asymptomatic lesion (expected mortality rate 5-20%)', 'role': 'assistant'}]