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: Surgery
Most common cause of Abdominal Aoic Aneurysm is: 
Select and explain. 
A. Atherosclerosis, B. Trauma, C. Syphilis, D. Vasculitis
A: Atherosclerosis
Answer: A: Atherosclerosis 
Explanation: The abdominal aoa is commonly afftected by atheroma by the process of atherosclerosis. This atheroma causes intimal weaking leading to aneurysm. so atherosclerosis is the leading cause for Abdominal Aoic Aneurysm. Ref: Encyclopedia of Hea Diseases By M. I. Gabriel Khan. 2006, Page 27