You are answering a USMLE-style medical question. Question: A 24-year-old man with chronic back pain comes to the physician to establish care after moving to Florida. He complains of anxiety, nausea, abdominal cramping, vomiting, and diarrhea for three days. He denies smoking, drinking alcohol, and using illicit drugs. He appears restless. His temperature is 37°C (98.6°F), pulse is 110/min, and blood pressure is 150/86 mm Hg. Physical examination shows dilated pupils, diaphoresis, and piloerection. His abdominal exam shows diffuse mild tenderness. There is no rebound tenderness or guarding. His hemoglobin concentration is 14.5 g/dL, leukocyte count is 8,000/mm, and platelet count is 250,000/mm3; serum studies and urinalysis show no abnormalities. Which of the following is the most appropriate pharmacotherapy? Options: A) Lorazepam B) Naltrexone C) Methadone D) Naloxone " Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.