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: Physiology
[{'content': 'The best test for GFR is with \nSelect and explain. \nA. Inulin, B. Hippuric acid, C. Creatinine, D. PAH', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Properties of Inulin\n-\xa0\xa0\xa0\xa0\xa0\xa0\xa0 Easily filtered by kidney\n-\xa0\xa0\xa0\xa0\xa0\xa0\xa0 Not absorbed by kidney\n-\xa0\xa0\xa0\xa0\xa0\xa0\xa0 Not secreted by kidney\n-\xa0\xa0\xa0\xa0\xa0\xa0\xa0 Not metabolized by kidney\n-\xa0\xa0\xa0\xa0\xa0\xa0\xa0 Not synthesized by kidney\n-\xa0\xa0\xa0\xa0\xa0\xa0\xa0 Non-toxic\n-\xa0\xa0\xa0\xa0\xa0\xa0\xa0 Easily measurable\nThus it is the best substance to use for measurement of GFR.', 'role': 'assistant'}]