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: Dental
Normal facial index is: 
Select and explain. 
A. 65 - 75%, B. 75 - 80%, C. 80 - 90%, D. 100%
C: 80 - 90%
Answer: C: 80 - 90% 
Explanation: None