You are answering a USMLE-style medical question. Question: A 28-year-old man is brought to the emergency department because of a 3-day history of fever, chills, and generalized weakness. He has no cough. He was treated for a neck abscess 6 months ago. He takes no medications. He has smoked one pack of cigarettes daily for 10 years and drinks two to three beers daily. He has been using intravenous cocaine and heroin for 6 years. He appears ill. His temperature is 38.6°C (101.5°F), pulse is 112/min, respirations are 20/min, and blood pressure is 110/70 mm Hg. Examination shows track marks on both cubital fossae. There are retinal hemorrhages with pale centers. The lungs are clear to auscultation. A grade 3/6 holosystolic murmur is heard best at the lower left sternal border. Laboratory studies show: Hemoglobin 13.3 g/dL Leukocyte count 14,300/mm3 Platelet count 278,000/mm3 Serum Glucose 96 mg/dL Creatinine 1.0 mg/dL Total bilirubin 0.4 mg/dL AST 18 U/L ALT 22 U/L Transthoracic echocardiography shows multiple vegetations on the tricuspid valve and moderate tricuspid regurgitation. Two sets of blood cultures are collected. Which of the following is the most appropriate next step in management?" Options: A) Transesophageal echocardiography B) Intravenous vancomycin therapy C) X-ray of the chest D) CT pulmonary angiogram Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.