You are answering a USMLE-style medical question. Question: A 74-year-old man undergoes an open cholecystectomy. Surgery is performed under general anesthesia for which the patient is intubated with an endotracheal tube. Directly following the procedure, his temperature is 37°C (98.6°F), pulse is 80/min, and blood pressure is 110/80 mm Hg. He is extubated as soon as he showed signs of alertness. Five minutes later, he becomes unresponsive. He has type 2 diabetes mellitus, coronary artery disease, and hypertension. He underwent stenting of the right coronary artery 10 years ago. He smoked one pack of cigarettes daily for 40 years but quit 2 weeks ago for surgery. He drinks one to two beers daily. His current medications include metformin, enalapril, aspirin, atorvastatin, and a multivitamin. His temperature is 37°C (98.6°F), pulse is 102/min, respirations are 20/min, and blood pressure is 130/80 mm Hg. Pulse oximetry shows an oxygen saturation of 73%. He is put on a non-rebreather mask with an FiO2 of 100%. Three minutes later, he is still unresponsive. His arterial blood gas analysis shows: pH 7.32 PCO2 33 mm Hg PO2 73 mm Hg HCO3 22 mEq/L O2 saturation 73% Which of the following is the best next step in the management of this patient?" Options: A) Perform tracheostomy B) Continue using the non-rebreather mask C) Reintubate D) Start BiPAP Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.