You are answering a USMLE-style medical question. Question: A 39-year-old man presents to the emergency department because of progressively worsening chest pain and nausea that started at a local bar 30 minutes prior. The pain radiates to the epigastric area. He has a 5-year history of untreated hypertension. He has smoked 1 pack of cigarettes daily for the past 5 years and started abusing cocaine 2 weeks before his emergency room visit. The patient is diaphoretic and in marked distress. What should be the first step in management? Options: A) Diltiazem B) Labetalol C) Propranolol D) Reassurance and continuous monitoring Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.