You are answering a USMLE-style medical question. Question: A 60-year-old man comes to the physician because of a 2-month history of cough productive of yellow sputum with occasional streaks of blood. He has a history of pulmonary tuberculosis. He is afebrile. Pulmonary examination shows inspiratory crackles at the left infraclavicular area. An x-ray of his chest shows a radiopaque mass in the left upper lung lobe that shifts upon repositioning. A sputum sample does not grow acid-fast bacteria despite multiple cultures. Which of the following is the most likely cause of this patient's condition? Options: A) Asbestos inhalation B) Neoplastic transformation C) Opportunistic colonization D) Abscess formation Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.