You are answering a USMLE-style medical question. Question: A 15-year-old boy is brought to the emergency department because of severe abdominal pain and vomiting for 8 hours. He has had around 3–4 episodes of greenish colored vomit during this period. He has major depressive disorder with psychosis. His mother has Graves' disease. Current medications include sertraline and haloperidol. He appears uncomfortable. His temperature is 37.3°C (99.1°F), pulse is 87/min, and blood pressure is 118/72 mm Hg. He is diagnosed with acute appendicitis and is taken to the operating room for an emergency laparoscopic appendectomy. The appendix is gangrenous and perforated with purulent fluid in the pelvis. Just after the appendiceal base is ligated, the patient shows muscle rigidity and profuse diaphoresis. His temperature is 39.1°C (102.4°F), pulse is 130/min, and blood pressure is 146/70 mm Hg. The pupils are equal and reactive to light. The end-tidal CO2 is 85 mm Hg. Which of the following is the most appropriate treatment for this patient's condition? Options: A) Dantrolene B) Bromocriptine C) Cyproheptadine D) Surgical embolectomy Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.