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: Radiology
Rim sign in IVP is seen in 
Select and explain. 
A. Polycystic Kidney, B. Hydronephrosis, C. Chronic pyelonephritis, D. Hypernephroma
B: Hydronephrosis
Answer: B: Hydronephrosis 
Explanation: B i.e. Hydronephrosis