**Core Concept**
Membranous glomerulonephritis (MGN) is a type of glomerulonephritis characterized by immune complex deposition in the glomerular basement membrane, leading to thickening and proteinuria. In systemic lupus erythematosus (SLE), MGN is a common manifestation due to autoantibody-mediated immune complex formation.

**Why the Correct Answer is Right**
Membranous glomerulonephritis in SLE is classified as **Class V** in the WHO classification of glomerulonephritis. Class V is defined by subepithelial immune complex deposits, primarily involving IgG and C3, which cause glomerular basement membrane thickening and proteinuria. This form is often associated with anti-PLA2R antibodies or other autoantibodies in SLE, leading to a membranous pattern on immunofluorescence. The disease is typically non-proliferative and presents with nephrotic-range proteinuria.

**Why Each Wrong Option is Incorrect**
Option A: Class II (membranoproliferative glomerulonephritis) is characterized by proliferative changes and C3 deposits, not immune complex deposition in the basement membrane.
Option B: Class III (membranoproliferative) involves both mesangial proliferation and immune complex deposition, but the histopathology differs from MGN.
Option C: Class IV (focal segmental glomerulosclerosis) features sclerosis of glomerular segments and is not seen in SLE-related MGN.

**Clinical Pearl / High-Yield Fact**
In SLE, membranous glomerulonephritis is most commonly **Class V**, and it is the most common glomerulonephritis in SLE patients. Always remember: **"Class V = Membranous"**, and it presents with nephrotic syndrome and often responds to immunosuppression.

✓ Correct Answer: D. Class V