Glomerular Diseases USMLE Step 1 Practice Question

A 28-year-old woman with a 3-year history of systemic lupus erythematosus presents to the nephrology clinic for evaluation of progressive renal disease. She reports new-onset bilateral lower extremity edema and foamy urine. Vital signs are BP 148/92 mmHg, HR 86 bpm, RR 16, temp 37.0°C, SpO2 99% on room air. Laboratory studies show serum creatinine 0.9 mg/dL, serum albumin 2.2 g/dL, and 24-hour urine protein 5.8 g. Serum complement levels are depressed (C3 22 mg/dL, C4 8 mg/dL). Urinalysis reveals 3+ protein and occasional RBCs with no casts. Kidney biopsy shows a mixture of basement membrane thickening with spike-and-dome lesions alongside proliferation of glomerular endocapillary cells with numerous subendothelial immune complexes. Which WHO/ISN-RPS classification of lupus nephritis is most consistent with these findings?