Pathology

A 7-year-old boy presents with bilateral swelling around his eyes. His parents state that the child's eyes have become "puffy" over the past several weeks, and his urine has become cocoa-colored. Physical examination reveals bilateral periorbital edema, but peripheral edema is not found. The boy is afebrile and his blood pressure is slightly elevated. A urinary dipstick reveals mild proteinuria, while microscopic examination of the boy's urine reveals hematuria with red blood cell casts. Laboratory tests reveal increased ASO titers and decreased serum C3 levels, but C2 and C4 levels are normal. A throat swab for streptococci is negative. A microscopic section from the kidney reveals increased numbers of cells within the glomeruli. An electron microscopic section of the kidney reveals large electron-dense deposits in the glomeruli that are located between the basement membrane and the podocytes. The foot processes of the podocytes are otherwise unremarkable. Which one of the following renal diseases most likely produced the abnormalities in this young boy?