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: Pathology
[{'content': 'Ascending aorta involvement is the commonest site of which aneurysm - \nSelect and explain. \nA. Syphilitic, B. Atherosclerotic, C. Mycotic, D. None of the above', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Direct lines… “The obliterative endarteritis characteristic of late-stage syphilis shows a predilection for small vessels, including those of the vasa vasorum of the thoracic aorta.”\nAtherosclerosis affects abdominal aorta most commonly. Traumatic aneurysm can affect any site of the aorta. Berry aneurysm affects the circle of Willis.', 'role': 'assistant'}]