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: Surgery
Normal capacity of the renal pelvis is - 
Select and explain. 
A. 7 ml., B. 10 ml, C. 15 ml, D. 20 ml
A: 7 ml.
Answer: A: 7 ml. 
Explanation: Ans. is 'a' i.e., 7 ml