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
What percent of cases with injury to kidney require surgical exploration - 
Select and explain. 
A. 20%, B. 90%, C. 50%, D. 70%
A: 20%
Answer: A: 20% 
Explanation: Ans. is 'a' i.e., 20% "Surgical exploration is needed in less than 10 percent of closed injuries and is indicated if either there a signs of progressive blood loss or there is an expanding mass in the loin."- Bailey 25/e