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': 'Normal filtration fraction is around: \nSelect and explain. \nA. 0.05, B. 0.1, C. 0.2, D. None of the above', 'role': 'user'}, {'content': "Answer: C \nExplanation: The ratio of the GFR to the RPF, the filtration fraction, is normally 0.16 to 0.20. The GFR varies less than the RPF. When there is a fall in systemic blood pressure, the GFR falls less than the RPF because of efferent aeriolar constriction, and consequently the filtration fraction rises. Ref: Ganong's Review of Medical Physiology 23rd edition, Chapter 38.", 'role': 'assistant'}]