You are answering a USMLE-style medical question. Question: A 55-year-old woman with a history of HIV presents to the emergency department with progressive dyspnea, fever, and dry cough for the past 4 days. She has not been compliant with antiretroviral or prophylactic medication. On evaluation, the patient is in moderate respiratory distress. The temperature is 38.8°C (102.0°F), the blood pressure is 124/82 mm Hg, the pulse is 96/min, and the respiratory rate is 20/min. Pulse oximetry is 92% on 4 L oxygen by nasal cannula. Her CD4 count is 180 cells/μL. IV antibiotics and glucocorticoids are administered. After 30 minutes, the patient develops severe respiratory distress. Repeat vital signs show: temperature 38.3°C (101.0°F), blood pressure 80/50 mm Hg, pulse 104/min, respiration rate 32/min and pulse oximetry 85% on nasal cannula. The trachea deviates to the left. Breath sounds are absent on the right side and the neck veins are distended. Telemetry shows sinus tachycardia. Which of the following is the best next step in the management of this patient? Options: A) Discontinue antibiotics B) Perform an arterial blood gas C) Needle thoracostomy D) Stat chest X-ray Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.