You are answering a USMLE-style medical question. Question: A 40-year-old man presents to the emergency department with altered mental status. He has a history of cirrhosis of the liver secondary to alcoholism. He started becoming more confused a few days ago and it has been getting gradually worse. His temperature is 98.8°F (37.1°C), blood pressure is 134/90 mmHg, pulse is 83/min, respirations are 15/min, and oxygen saturation is 98% on room air. Physical exam reveals a distended abdomen that is non-tender. Neurological exam is notable for a confused patient and asterixis. Laboratory values are ordered as seen below. Serum: Na+: 139 mEq/L Cl-: 100 mEq/L K+: 3.3 mEq/L HCO3-: 22 mEq/L BUN: 20 mg/dL Glucose: 59 mg/dL Creatinine: 1.1 mg/dL Ca2+: 10.2 mg/dL Which of the following is the best next treatment for this patient? Options: A) Dextrose B) Lactulose C) Potassium D) Rifaximin Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.