This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: C.V.S., Subject name: Medicine
[{'content': 'This patient presented with chest pain. What is the diagnosis? \nSelect and explain. \nA. Acute pulmonary embolism, B. Hypertrophic cardiomyopathy, C. Ascending aortic aneurysm, D. Coarctation of the aorta', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Answer C. Ascending aortic aneurysmA widened mediastinum is visible on chest radiography. The patient was diagnosed with a 9.5-cm ascending aortic aneurysm.', 'role': 'assistant'}]