This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Nephritic & Nephrotic Syndrome, Subject name: Pediatrics
[{'content': "In a case of glomerulonephritis (GN) , C3 is normal in all the following except? \nSelect and explain. \nA. Diffuse lupus nephritis, B. Good pasteur's syndrome, C. IgA nephropathy, D. HSP", 'role': 'user'}, {'content': 'Answer: A \nExplanation: Low C3 nephritis is observed in: Post-infectious GN, MPGN(Membranoproliferative GN) SLE Subacute bacterial endocarditis Cryoglobulinemia, shunt nephritis', 'role': 'assistant'}]