**Core Concept**
Glomerular diseases can be broadly classified based on the presence or absence of crescent formation, which is a hallmark of severe glomerular injury. Crescent formation is characterized by the accumulation of proliferating parietal epithelial cells and monocytes/macrophages in the Bowman's space, leading to a crescent-shaped structure.

**Why the Correct Answer is Right**
Rapidly progressive glomerulonephritis (RPGN) is a clinical syndrome characterized by rapid deterioration of renal function, often accompanied by severe crescentic glomerulonephritis. The formation of crescents in RPGN is due to the activation of the coagulation cascade, leading to the deposition of fibrin in the Bowman's space, which is then infiltrated by monocytes/macrophages and parietal epithelial cells. This process is mediated by the increased expression of pro-inflammatory cytokines and chemokines, such as IL-1β and TNF-α, which attract immune cells to the glomerulus.

**Why Each Wrong Option is Incorrect**
**Option A:** Minimal change disease is characterized by the loss of foot processes of podocytes and the absence of crescent formation. It is the most common cause of nephrotic syndrome in children and is often associated with a good prognosis.
**Option C:** Focal and segmental glomerulosclerosis (FSGS) is a disease characterized by the scarring of glomeruli, but it is not typically associated with crescent formation. FSGS can be primary or secondary to other conditions, such as hypertension or obesity.
**Option D:** The term "Rapidly non progressive glomerulonephritis" is not a recognized clinical entity. The correct term is Rapidly progressive glomerulonephritis (RPGN), which is characterized by a rapid decline in renal function and the presence of crescentic glomerulonephritis.

**Clinical Pearl / High-Yield Fact**
Crescent formation in glomerulonephritis is a marker of severe glomerular injury and is often associated with a poor prognosis. The presence of crescents on renal biopsy is a key feature that distinguishes RPGN from other forms of glomerulonephritis.

**✓ Correct Answer: B. Rapidly progressive glomerulonephritis**