**Core Concept**
Rapidly progressive glomerulonephritis (RPGN) is a severe kidney disease characterized by rapid loss of kidney function, often leading to kidney failure. The underlying pathophysiology involves inflammation and damage to the glomeruli, the filtering units of the kidney. The treatment of RPGN aims to halt the progression of kidney damage and preserve renal function.

**Why the Correct Answer is Right**
The first-line treatment of RPGN typically involves the administration of corticosteroids, such as methylprednisolone, to reduce inflammation and suppress the immune system. Corticosteroids work by inhibiting the production of pro-inflammatory cytokines and reducing the activation of immune cells, such as T cells and macrophages, that contribute to glomerular damage. This approach is often combined with immunosuppressive agents, such as cyclophosphamide, to further suppress the immune response.

**Why Each Wrong Option is Incorrect**
**Option A:**
This option is incorrect because while supportive care, such as dialysis, may be necessary for patients with RPGN, it does not address the underlying cause of the disease.

**Option B:**
This option is incorrect because while angiotensin-converting enzyme inhibitors (ACEIs) or angiotensin receptor blockers (ARBs) may be used to manage hypertension and proteinuria in patients with RPGN, they do not treat the underlying inflammatory process.

**Option C:**
This option is incorrect because while pulse methylprednisolone may be used in the treatment of RPGN, it is not the first-line treatment and is often used in conjunction with other immunosuppressive agents.

**Clinical Pearl / High-Yield Fact**
It is essential to recognize that RPGN is a medical emergency requiring prompt treatment to preserve renal function. Early recognition and initiation of therapy can significantly improve outcomes in patients with RPGN.

**Correct Answer: C. Pulse methylprednisolone**