You are answering a USMLE-style medical question. Question: Two days after admission to the hospital for treatment of acute myelogenous leukemia, a 35-year-old man develops nausea, vomiting, fatigue, and muscle cramps. He has a history of diet-controlled type 2 diabetes mellitus. He has smoked one-half pack of cigarettes daily for 15 years and reports occasionally using marijuana. His temperature is 38.7°C (101.1°F), pulse is 85/min, respirations are 25/min, and blood pressure is 110/65 mm Hg. Laboratory studies show: Leukocyte count 16,000/mm3 Hemoglobin 13.4 g/dL Platelet count 180,000/mm3 Serum Na+ 134 mEq/L K+ 5.9 mEq/L Cl- 101 mEq/L HCO3- 24 mEq/L Urea nitrogen 27 mg/dL Uric acid 11.2 mg/dL Creatinine 2.2 mg/dL Glucose 134 mg/dL Ca2+ 6.8 mg/dL Mg2+ 1.8 g/dL Phosphorus 8.9 mg/dL Which of the following would have been most effective in preventing this patient's current symptoms?" Options: A) Urine alkalinization B) Rasburicase C) Allopurinol D) Intravenous hydration Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.