<s>[INST] context: The slow progression of aortoiliac atherosclerotic occlusive disease is usually associated with the development of collateral flow through the lumbar branches of the aorta, anastomosing via retroperitoneal branches of the gluteal arteries with the profunda femoris arteries in the legs. This network of collateral vessels provides sufficient blood flow to nourish the extremities at rest but cannot prevent claudication of the upper and lower muscle groups of the leg during exercise. Sexual impotence, also part of the Leriche syndrome, is believed to be a result of bilateral stenosis or occlusion of the hypogastric (internal iliac) arteries. Retrograde ejaculation can occur after disruption of the sympathetic chain overlying the distal aorta and left iliac and can occur after dissection around these vessels during vascular reconstructions. Gangrene of the feet or toes is rarely seen unless distal embolization of atherosclerotic material from the aorta occludes the pedal or digital arteries. Dependent rubor is usually a sign of significant ischemia resulting from lower extremity occlusive and not aortoiliac disease. Causalgia or reflex sympathetic dystrophy is a disorder of the sympathetic nervous system that can affect the upper or lower extremities. [/INST] question: Symptoms or signs of atherosclerotic occlusive disease of the bifurcation of the abdominal aorta (Leriche syndrome) include | options: A: Claudication of the buttock and thigh B: Causalgia of the lower leg C: Retrograde ejaculation D: Gangrene of the feet | answer: A </s>