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
Most common cause of aoic aneurysm is ? 
Select and explain. 
A. Atherosclerosis, B. Syphilis, C. Trauma, D. Congenital
A: Atherosclerosis
Answer: A: Atherosclerosis 
Explanation: Ans. is 'a' i.e., Atherosclerosis