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
Calculate the filtration,if GFR = 125 ml / min and renal plasma = 625 ml / min 
Select and explain. 
A. 5%, B. 20%, C. 50%, D. 10%
B: 20%
Answer: B: 20% 
Explanation: None