You are answering a USMLE-style medical question. Question: A 75-year-old man comes to the physician for the evaluation of progressive shortness of breath and fatigue over the past month. He reports that he cannot climb more than one flight of stairs without experiencing shortness of breath and dizziness. He has hypertension and hyperlipidemia. He has smoked one pack of cigarettes daily for the past 50 years. He does not drink alcohol. His medications include enalapril, atorvastatin, and low-dose aspirin. His temperature is 37°C (98.6°F), pulse is 70/min, respirations are 18/min, and blood pressure is 100/80 mm Hg. Physical examination shows weak peripheral pulses. Cardiac examination is shown. Which of the following is the most likely diagnosis? Options: A) Tricuspid valve stenosis B) Mitral valve prolapse C) Mitral valve stenosis D) Aortic valve stenosis Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.