This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pathology
Which of the following is the most consistent feature of rapidly progressing glomerulonephritis (RPGN)? 
Select and explain. 
A. Crescent formation, B. Mesangial cell proliferation, C. IgAdeposition, D. Loss offoot processes
A: Crescent formation
Answer: A: Crescent formation 
Explanation: Ans: A. Crescent formationRapidly Progressive (Crescentic) Glomerulonephritis:Most common histologic - Presence of crescents in most glomeruli (crescentic glomerulonephritis).Crescents:Produced by proliferation of parietal cells & infiltration of monocytes & macrophages.