**Core Concept**
Alport syndrome is a genetic disorder characterized by glomerulonephritis, end-stage kidney disease, and hearing loss. It is caused by mutations in the COL4A3, COL4A4, or COL4A5 genes, which encode for type IV collagen. The pathophysiology of Alport syndrome involves the abnormal production of type IV collagen, leading to the disruption of the glomerular basement membrane and subsequent kidney damage.

**Why the Correct Answer is Right**
The correct answer is **C.** The characteristic light microscopical feature of Alport syndrome is the **thickening of the glomerular basement membrane (GBM)**, which is a result of the abnormal deposition of type IV collagen. This thickening leads to the disruption of the normal filtration function of the glomerulus, resulting in proteinuria and progressive kidney disease. The GBM thickening is a hallmark of Alport syndrome and is often used as a diagnostic criterion.

**Why Each Wrong Option is Incorrect**
**Option A:** The presence of **mesangial interposition** is actually a feature of membranoproliferative glomerulonephritis, not Alport syndrome.

**Option B:** The **lamellation of the GBM** is a feature of Alport syndrome, as the abnormal type IV collagen leads to the formation of a lamellated or "onion-skin" appearance of the GBM.

**Option D:** The **electron-dense deposits** are not a characteristic feature of Alport syndrome. These deposits are typically seen in other types of glomerulonephritis, such as membranous nephropathy.

**Clinical Pearl / High-Yield Fact**
Alport syndrome is an X-linked dominant disorder, meaning that females can be carriers and males are more severely affected. This knowledge is crucial for diagnosing and counseling affected families.

**Correct Answer: C.**