**Core Concept**
The patient's presentation suggests a systemic disease characterized by renal involvement, leading to proteinuria and hypertension, along with skin manifestations.

**Why the Correct Answer is Right**
The patient's symptoms are consistent with membranous nephropathy (MN), a type of glomerulonephritis characterized by the deposition of immune complexes on the subepithelial side of the glomerular basement membrane. This leads to podocyte damage, resulting in subnephrotic proteinuria. The skin manifestations, such as edema and ulceration, are likely due to nephrotic syndrome. The hypertension is also a common finding in patients with kidney disease.

**Why Each Wrong Option is Incorrect**
* **Option A:** This could be membranoproliferative glomerulonephritis (MPGN), but MPGN typically presents with nephritic syndrome (hematuria, hypertension, and renal insufficiency) rather than nephrotic syndrome.
* **Option B:** Focal segmental glomerulosclerosis (FSGS) is a common cause of nephrotic syndrome, but it typically presents with more significant proteinuria and is less likely to be associated with skin manifestations.
* **Option C:** Minimal change disease is a common cause of nephrotic syndrome in children, but it is less likely to present with skin manifestations in adults.
* **Option D:** Rapidly progressive glomerulonephritis (RPGN) is a medical emergency characterized by rapid loss of renal function and is less likely to present with subnephrotic proteinuria.

**Clinical Pearl / High-Yield Fact**
Membranous nephropathy is the most common cause of nephrotic syndrome in adults, and it is often associated with autoimmune disorders, such as lupus or rheumatoid arthritis.

**Correct Answer: B. Focal segmental glomerulosclerosis (FSGS)**