You are answering a USMLE-style medical question. Question: A 56-year-old man with a history of pancreatic cancer presents to the surgical intensive care unit following a pancreaticoduodenectomy. Over the next 3 days, the patient's drainage output is noted to exceed 1 liter per day. In the early morning of postoperative day 4, the nurse states that the patient is difficult to arouse. His temperature is 99.5°F (37.5°C), blood pressure is 107/88 mmHg, pulse is 120/min, respirations are 17/min, and oxygen saturation is 98% on room air. His skin and mucous membranes are dry on physical exam. Laboratory values are ordered as seen below. Serum: Na+: 154 mEq/L Cl-: 100 mEq/L K+: 4.3 mEq/L HCO3-: 27 mEq/L BUN: 20 mg/dL Glucose: 99 mg/dL Creatinine: 1.1 mg/dL Which of the following is the best next step in management? Options: A) 0.9% saline IV B) 5% dextrose IV C) 5% dextrose IV with 0.45% saline IV D) Oral free water replacement Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.