This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: G.I.T., Subject name: Pathology
70 year old man has abdominal pain with mass in abdomen. Angiography reveals aneurysm of aorta. Most likely cause is: 
Select and explain. 
A. Trauma, B. Atherosclerosis, C. Syphilis, D. Congenital
B: Atherosclerosis
Answer: B: Atherosclerosis 
Explanation: Ans. is 'b' Atherosclerosis Most common cause of abdominal aortic aneurysm - Atherosclerosis (90%).Other frequently asked questions about aortic aneurysm.Most common cause of aortic aneurysm (overall) = Atherosclerosis. *Most common cause of ascending aortic aneurysm = Cystic medial necrosis. *Most common cause of descending aortic aneurysm = Atherosclerosis. *Most common cause of aneurysm of aortic arch = Atherosclerosis. *Syphilitic aneurysm affect = Ascending aorta. *Aneurysm of Takayasu arteritis affects = Aortic arch. *