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 aoa involvement is the commonest site of which aneuryam - \nSelect and explain. \nA. Syphilitic, B. Atherosclerotic, C. Mycotic, D. None of the above', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., Syphilitic", 'role': 'assistant'}]