**Core Concept**
Membranoproliferative Glomerulonephritis (MPGN) type 1 is a type of glomerulonephritis characterized by the thickening of the glomerular basement membrane (GBM) and proliferation of mesangial cells. This condition is often associated with immune complex deposition and complement activation. The "tram-track" appearance of the GBM is a distinctive histopathological feature of MPGN type 1.

**Why the Correct Answer is Right**
The "tram-track" appearance in MPGN type 1 is due to the duplication of the GBM, resulting from the deposition of immune complexes and complement activation. This leads to the formation of two distinct layers of the GBM, which appear as parallel, thickened bands under light microscopy. The proliferation of mesangial cells and the deposition of immune complexes also contribute to the characteristic histopathological features of MPGN type 1.

**Why Each Wrong Option is Incorrect**
**Option A:** Membranous nephropathy is characterized by the thickening of the GBM due to immune complex deposition, but it does not typically exhibit a "tram-track" appearance. The GBM is uniformly thickened in membranous nephropathy, rather than showing a layered or duplicated appearance.
**Option B:** Focal Segmental Glomerulosclerosis (FSGS) is a condition characterized by the sclerosis of segments of the glomerulus, but it does not typically show a "tram-track" appearance of the GBM. FSGS is often associated with podocyte injury and effacement.
**Option C:** Minimal-Change Disease is a condition characterized by the loss of foot processes of podocytes, but it does not typically show a "tram-track" appearance of the GBM. Minimal-Change Disease is often associated with nephrotic syndrome and is typically diagnosed by electron microscopy.

**Clinical Pearl / High-Yield Fact**
The "tram-track" appearance of the GBM in MPGN type 1 is a classic histopathological feature of this condition. It is essential to recognize this feature, along with other histopathological characteristics, to make an accurate diagnosis of MPGN type 1.

**✓ Correct Answer: A. Membranoproliferative Glomerulonephritis type 1**