You are answering a USMLE-style medical question. Question: A 64-year-old man comes to the emergency department because of a 2-day history of lower back pain, fever, and chills. He has had nausea but no vomiting during this time. He has hypertension, chronic kidney disease, and type 2 diabetes mellitus. Three months ago, he underwent amputation of his left third toe because of a non-healing ulcer. He has smoked a pack of cigarettes daily for 48 years. Current medications include hydrochlorothiazide, metoprolol, and insulin. His temperature is 39.4°C (102.9°F), pulse is 102/min, blood pressure is 150/94 mm Hg, and respirations are 18/min. Examination shows a 1-cm (0.4-in) round ulcer on the sole of his right foot. There is costovertebral angle tenderness on the left side. The abdomen is soft. Laboratory studies show: Hemoglobin 11.5 g/dL Leukocyte count 19,000/mm3 Serum Na+ 140 mEq/L Cl− 102 mEq/L K+ 5.0 mEq/L HCO3− 25 mEq/L Urea nitrogen 65 mg/dL Creatinine 2.4 mg/dL Glucose 240 mg/dL Urine Blood 1+ Protein 1+ WBC 100/hpf Nitrite 2+ WBC casts numerous Urine and blood samples for culture and sensitivity tests are obtained. Which of the following is the most appropriate next step in management?" Options: A) Inpatient treatment with intravenous ciprofloxacin B) Outpatient treatment with oral levofloxacin C) Outpatient treatment with trimethoprim-sulfamethoxazole D) Initiate hemodialysis Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.