You are answering a USMLE-style medical question. Question: A 67-year-old man presents to his primary care physician for erectile dysfunction. He states that for the past month he has been unable to engage in sexual intercourse with his wife despite having appropriate sexual desire. He also endorses deep and burning buttock and hip pain when walking, which is relieved by rest. The patient states that he does not have erections at night or in the morning. His past medical history is notable for diabetes, coronary artery disease, and hypertension, and he has a 40 pack-year smoking history. Physical exam is notable for weak lower extremity and femoral pulses. Which of the following is the most specific etiology of this patient’s symptoms? Options: A) Anxiety B) Aortoiliac atherosclerosis C) Spinal stenosis D) Vascular claudication Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.