**Core Concept**
Membranous glomerulopathy is a type of glomerular disease characterized by the deposition of immune complexes on the subepithelial side of the glomerular basement membrane, leading to thickening and alteration of the glomerular filtration barrier. This condition is often associated with autoimmune disorders, infections, and malignancies.

**Why the Correct Answer is Right**
Membranous glomerulopathy is characterized by the presence of subepithelial immune complex deposits, which are visible on electron microscopy as "humps" or "spikes" on the glomerular basement membrane. This leads to a decrease in the glomerular filtration surface area and an increase in the glomerular filtration resistance, resulting in proteinuria and hematuria. The disease often presents with nephrotic syndrome, which is characterized by massive proteinuria, hypoalbuminemia, hyperlipidemia, and edema.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because membranous glomerulopathy is characterized by the deposition of immune complexes on the subepithelial side of the glomerular basement membrane, not the subendothelial side.
* **Option B:** This option is incorrect because membranous glomerulopathy is often associated with autoimmune disorders, infections, and malignancies, not just IgA nephropathy.
* **Option C:** This option is incorrect because membranous glomerulopathy is characterized by the presence of subepithelial immune complex deposits, not mesangial interposition.

**Clinical Pearl / High-Yield Fact**
Membranous glomerulopathy is often associated with the presence of circulating immune complexes and can be diagnosed using immunofluorescence and electron microscopy. It is essential to distinguish membranous glomerulopathy from other causes of nephrotic syndrome, such as minimal change disease and focal segmental glomerulosclerosis.

**Correct Answer: A.**