A 24-yeаr-оld femаle presents with а rash and swоllen jоints. She had been previously healthy, and the only medication that she currently takes is acetaminophen. A review of systems includes recent fevers and a 5-pound weight loss in the past month; she is also experiencing photosensitivity and hematuria. She denies oral ulcers, nasal congestion/discharge, ear pain, pleuritic symptoms, chest pain, neurologic symptoms, bruising, and bleeding. On physical examination, vital signs are: T: 100.8ºF; BP: 130/85 mmHg; HR: 82/min; RR: 16/min. She has a malar rash as well as diffusely swollen, warm, and tender joints. Her cardiopulmonary exam is unremarkable. She has no costovertebral angle tenderness bilaterally. Trace pedal edema is noted bilaterally. Initial diagnostic testing reveals: Erythrocyte sedimentation rate 50 mm/hour (↑) Hemoglobin 11 g/dL (↓) Anti-double-stranded DNA antibodies Positive Platelet count 200,000 cells/ mm3 White blood cell count 12,000 cells/mm3 (↑) Chest x-ray Normal Urinalysis/Urine culture Numerous red blood cells. Red blood cell casts. Urine culture: No bacterial growth. Based on this information, which of the following conditions is the most likely diagnosis for this patient?