This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Radiology
[{'content': 'Scan used to estimate collecting system dilatation is \nSelect and explain. \nA. 99m Tc- DTPA scan, B. MAG 3 scan, C. DMSA scan, D. Hippuran scan', 'role': 'user'}, {'content': 'Answer: A \nExplanation: (Ref: Grainger&;s diagnostic radiology, 6th ed; page 134)', 'role': 'assistant'}]