**Core Concept**
The child's presentation of recurrent polyuria, short stature, and bilateral small kidneys on ultrasound is suggestive of a chronic kidney disease, specifically a congenital nephrotic syndrome or a chronic glomerulonephritis. The elevated serum creatinine level indicates impaired renal function.

**Why the Correct Answer is Right**
The child's symptoms and laboratory findings are consistent with **Focal Segmental Glomerulosclerosis (FSGS)**, a common cause of nephrotic syndrome in children. FSGS is characterized by the scarring of glomeruli, leading to proteinuria and eventually renal failure. The presence of small kidneys on ultrasound is a hallmark of chronic kidney disease.

**Why Each Wrong Option is Incorrect**
**Option A:** **Minimal Change Disease (MCD)** typically presents with nephrotic syndrome in children but is often responsive to corticosteroid therapy, which is not indicated in this case.

**Option B:** **Membranoproliferative Glomerulonephritis (MPGN)** is a type of glomerulonephritis that can cause chronic kidney disease but is less common in children and typically presents with hematuria and proteinuria.

**Option C:** **Alport Syndrome** is a genetic disorder that affects the kidneys, ears, and eyes but typically presents with hematuria and hearing loss in early childhood.

**Clinical Pearl / High-Yield Fact**
FSGS is one of the leading causes of nephrotic syndrome in children and is often associated with a poor prognosis, with many patients progressing to end-stage renal disease.

**Correct Answer: C. Alport Syndrome.**