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
What percentage of cardiac output is supplied to kidneys? 
Select and explain. 
A. 10%, B. 20%, C. 30%, D. None of the above
B: 20%
Answer: B: 20% 
Explanation: The paired renal aeries take 20% of cardiac output to supply organs that represent less than one-hundredth of total body weight. Ref: Gray's anatomy 40th edition, Chapter 91.