You are answering a USMLE-style medical question. Question: A 34-year-old patient is brought to the emergency room after a motor vehicle accident. An EKG shows sinus tachycardia and chest radiograph reveals an enlarged cardiac silhouette. While observing sinus tachycardia on the patient's telemetry, you note that the radial pulse cannot be palpated during inspiration. What should be the next step in management of this patient? Options: A) Pericardiocentesis B) Chest CT scan C) Pericardial window D) Insert chest tube Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.