You are answering a USMLE-style medical question. Question: A 36-year-old woman presents with increased tiredness and lethargy for the past 4 weeks. Investigations show her hemoglobin level to be 8.6 gm/dL and serum creatinine of 4.6 mg/dL. The serum is negative for antinuclear antibodies (ANA) and positive for C3 nephritic factor. Urinalysis shows a 3+ proteinuria. The renal biopsy demonstrates hypercellular glomerulus with electron dense deposits along the glomerular basement membrane. What is the most likely cause? Options: A) Membrano proliferative glomerulonephritis (MPGN) B) Rapidly progressive glomerulonephritis (RPGN) C) Minimal change disease D) Membranous glomerulonephritis (MGN) Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.