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
Rule of Nine estimates : 
Select and explain. 
A. The extent of the burn., B. Degree of severity., C. Degree of infection., D. The extent of mortality.
A: The extent of the burn.
Answer: A: The extent of the burn. 
Explanation: None