**Core Concept**
Type I RPGN (rapidly progressive glomerulonephritis) is characterized by immune complex deposition in the glomeruli, typically due to anti-glomerular basement membrane (anti-GBM) antibodies. It is a form of primary glomerulonephritis with severe, acute onset, often leading to rapid loss of kidney function.

**Why the Correct Answer is Right**
Goodpasture's syndrome is a classic example of Type I RPGN, where autoantibodies against the α3 chain of type IV collagen in the glomerular basement membrane cause direct damage. These antibodies trigger complement activation and intense inflammation, leading to hematuria, proteinuria, and rapidly declining renal function. The condition is often associated with pulmonary hemorrhage and requires urgent treatment with immunosuppression and plasmapheresis.

**Why Each Wrong Option is Incorrect**
Option A: Cryoglobulinemia causes Type II RPGN due to immune complex deposition, not anti-GBM antibodies.
Option B: SLE (systemic lupus erythematosus) typically causes Type III RPGN via immune complex deposition, not anti-GBM.
Option D: Wegener's granulomatosis (now GPA) causes Type II or III RPGN with granulomatous inflammation and anti-neutrophil cytoplasmic antibodies (ANCA), not anti-GBM.

**Clinical Pearl / High-Yield Fact**
Remember: Anti-GBM disease = Goodpasture’s = Type I RPGN = pulmonary hemorrhage + rapidly progressive renal failure. Always think of "anti-GBM" when seeing rapidly progressive nephritis with lung involvement.

✓ Correct Answer: C. Goodpasture's syndrome