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
This patient presented with chest pain. What is the diagnosis? 
Select and explain. 
A. Acute pulmonary embolism, B. Hypertrophic cardiomyopathy, C. Ascending aortic aneurysm, D. Coarctation of the aorta
C: Ascending aortic aneurysm
Answer: C: Ascending aortic aneurysm 
Explanation: Answer C. Ascending aortic aneurysmA widened mediastinum is visible on chest radiography. The patient was diagnosed with a 9.5-cm ascending aortic aneurysm.