You are answering a USMLE-style medical question. Question: Two days after being admitted to the hospital following a fall, a 77-year-old woman complains of fatigue and headaches. During the fall she sustained a right-sided subdural hematoma. She has hypertension and hyperlipidemia. Her medications prior to admission were hydrochlorothiazide and atorvastatin. Vital signs are within normal limits. Physical and neurologic examinations show no abnormalities. Laboratory studies show: Serum Na+ 130 mEq/L K+ 4.0 mEq/L Cl- 103 mEq/L HCO3- 24 mEq/L Urea nitrogen 14 mg/dL Creatinine 1.1 mg/dL Osmolality 270 mOsmol/kg H2O Urine Sodium 45 mEq/L Osmolality 326 mOsmol/kg H2O A CT scan of the head shows an unchanged right-sided subdural hematoma. Which of the following is the most appropriate next step in management?" Options: A) Head elevation B) Tolvaptan C) Desmopressin D) Fluid restriction Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.