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: Surgery
During investigation of hydronephrosis, isotope renogram is useful mainly in - 
Select and explain. 
A. Detecting vesicoureteric reflux, B. Anatomical definition, C. Distinguishing between non-obstructed system, D. Identifying ectopic kidney tissue
C: Distinguishing between non-obstructed system
Answer: C: Distinguishing between non-obstructed system 
Explanation: None