Correct Response: D. Aneurysms are bulges or widenings in a blood vessel caused by a weakness in the blood vessel wall. Because of this structural weakness, aneurysms are prone to rupturing and causing blood to hemorrhage into surrounding tissues. If such ruptures occur in the brain, it can lead to a stroke. A blood clot that forms in a blood vessel (A) is a thrombus. Deposits of plaque on the walls of arteries (B) are found in atherosclerosis and are known as atheromas. An abnormal connection between an artery and a vein (C) is an arteriovenous fistula and can lead to decreased oxygen delivery to surrounding tissues because capillaries in the region are bypassed.
