<prompt> Serum C3 is persistently low in the following except-Post streptococcal glomerulonephritisMembranoproliferative glomerulonephritisLupus nephritisGlomerulonephritis related to bacterial endocarditis  <response>: Lupus nephritis: the significance of serological tests at the time of biopsy. ... As compared with a group of lupus patients without nephritis, patients with nephritis had lower serum complement C3 p less than 0.05 and C4 p less than 0.005 levels and higher serum DNA binding activity p less than 0.001 Ref Harrison20th edition pg 277 