A 76 year old man suddenly collapsed and died. At post mortem exam, a retroperitoneal hematoma due to ruptured aortic aneurysm was noted. What is the most likely underlying cause of the aortic aneurysm?

The key is A. Atheroma. [Any condition that causes the walls of the arteries to weaken can lead to an aneurysm. Atherosclerosis is the leading cause. Others are high blood pressure, and smoking. Deep wounds, injuries, or infections can also cause blood vessels to bulge].