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
[{'content': 'GFR is measured with which of the following? \nSelect and explain. \nA. Iodohippurate, B. Tc 99m – DTPA, C. Tc 99m – MAG3, D. Tc 99m – DMSA', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]