**Core Concept**
Membranous glomerulonephritis in Systemic Lupus Erythematosus (SLE) is a type of immune complex-mediated glomerulonephritis characterized by the deposition of immune complexes on the glomerular basement membrane, leading to thickening and alteration of the membrane.

**Why the Correct Answer is Right**
In SLE, membranous glomerulonephritis is caused by the deposition of immune complexes containing anti-GBM (glomerular basement membrane) antibodies and complement components, which activate the complement cascade and lead to the recruitment of inflammatory cells, resulting in the characteristic thickening of the glomerular basement membrane. This process is mediated by the activation of the classical pathway of complement, which involves the sequential activation of C1, C4, and C2.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect as membranous glomerulonephritis is not typically associated with crescent formation, which is more characteristic of rapidly progressive glomerulonephritis.
**Option B:** This option is incorrect as membranous glomerulonephritis is not typically associated with the deposition of fibrin, which is more characteristic of fibrillary glomerulonephritis.
**Option C:** This option is incorrect as membranous glomerulonephritis is not typically associated with the deposition of amyloid, which is more characteristic of amyloidosis.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that membranous glomerulonephritis in SLE is often associated with the presence of anti-GBM antibodies, which can be detected through immunofluorescence studies. This can aid in the diagnosis and management of the condition.

**Correct Answer:** C.