You are answering a USMLE-style medical question. Question: A 79-year-old man presents to the office due to shortness of breath with moderate exertion and a slightly productive cough. He has a medical history of 25 years of heavy smoking. His vitals include: heart rate 89/min, respiratory rate 27/min, and blood pressure 120/90 mm Hg. The physical exam shows increased resonance to percussion, decreased breath sounds, and crackles at the lung base. Chest radiography shows signs of pulmonary hyperinflation. Spirometry shows a forced expiratory volume in the first second (FEV1) of 48%, a forced vital capacity (FVC) of 85%, and an FEV1/FVC ratio of 56%. According to these results, what is the most likely diagnosis? Options: A) Asthma B) Lymphangioleiomyomatosis C) Chronic obstructive pulmonary disease (COPD) D) Heart failure Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.