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
An elderly man presents with h/o abdomianl pain. He is found to have a fusiform dilatation of the descending aoa. Likely cause is: 
Select and explain. 
A. Trauma, B. Atherosclerosis, C. Right ventricular failure, D. Syphilitic aoitis
B: Atherosclerosis
Answer: B: Atherosclerosis 
Explanation: The is a case, of a symptomatic aneurysm suggested by pain as well as a fusiform dilatation of the aoa. 95% of the abdominal aneurysms are due to atherosclerosis. Ref: Bailey and Love's Sho Practice of Surgery, 25th Edition, Page 918 and 23rd Edition, Page 727.