**Core Concept**
Nephrotic syndrome in children is characterized by massive proteinuria, hypoalbuminemia, hyperlipidemia, and edema. The most common cause in children is a specific form of glomerular injury that leads to the loss of large amounts of albumin in the urine.

**Why the Correct Answer is Right**
The correct answer is **Minimal Change Disease (MCD)**, a type of glomerulonephritis that affects the glomerular basement membrane, leading to the loss of foot processes of podocytes and increased permeability to albumin. This results in massive proteinuria, hypoalbuminemia, and edema. The exact pathogenesis of MCD is not fully understood, but it is believed to involve immune system dysfunction and the release of cytokines that damage the glomerular basement membrane.

**Why Each Wrong Option is Incorrect**
**Option A:** Focal Segmental Glomerulosclerosis (FSGS) is another cause of nephrotic syndrome in children, but it is less common than MCD. FSGS is characterized by scarring of the glomeruli and is often associated with hypertension and hematuria.

**Option B:** Membranous nephropathy is a cause of nephrotic syndrome in adults, but it is rare in children. It is characterized by the deposition of immune complexes on the glomerular basement membrane, leading to increased permeability and proteinuria.

**Option C:** Membranoproliferative glomerulonephritis is a cause of nephritic syndrome, characterized by inflammation of the glomeruli and hematuria, but it is not a common cause of nephrotic syndrome in children.

**Option D:** Goodpasture syndrome is a rare autoimmune disorder characterized by glomerulonephritis and pulmonary hemorrhage, but it is not a common cause of nephrotic syndrome in children.

**Clinical Pearl / High-Yield Fact**
Minimal Change Disease is often responsive to corticosteroid therapy, and treatment typically involves a course of prednisone to reduce proteinuria and edema.

**Correct Answer:** C. Membranoproliferative glomerulonephritis