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
Impaired renal function is assessed by: 
Select and explain. 
A. DTPA, B. DMSA scan, C. Iodohippurate, D. MAG-3
D: MAG-3
Answer: D: MAG-3 
Explanation: Ans. MAG-3