A young girl presenting with generalized edema, significant proteinuria, absence of hematuria and hyaline and fatty casts is most likely to be suffering from Minimal change disease (Lipoid nephrosis), the most common type of Nephrotic Syndrome. In patients with Minimal change disease, C3 levels are normal and renal biopsy does not show any significant abnormalities except obliteration of epithelial foot processes. Therefore, No IgG Deposits or C3 deposition on renal biopsy is the best answer. Ref: Essential Pediatrics By O P Ghai, 6th Edition, Pages 446, 450