A 15-year-old male presents with sore throat, cough, headache, fatigue, and decreased appetite for 2 weeks, followed by cloudy red-brown urine without urinary frequency, urgency, or pain. He has eyelid and facial edema, blood pressure 150/90 mmHg, hemoglobin 102 g/dL, erythrocyte sedimentation rate (ESR) 45 mm/h, mildly elevated serum creatinine and blood urea nitrogen (BUN), markedly elevated anti-streptolysin O, and low complement C3. Acute glomerulonephritis is diagnosed. The cloudy red-brown urine is: