This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Urinary tract, Subject name: Pathology
In RPGN hallmark pathology is- 
Select and explain. 
A. Marked enlargement of mesangial tissue, B. Crescent formation, C. Thickening of basement membrane, D. All of the above
B: Crescent formation
Answer: B: Crescent formation 
Explanation: Distinctive lesions of proliferation are called crescents owing to their shape as they fill Bowman's space. Crescents are formed both by the proliferation of parietal cells and by the migration of monocytes/macrophages into Bowman's space Ref:- Robbins book of basic pathology 10th Ed. pg 532.