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
Which of the following is used in mixed dentition classification of malocclusion 
Select and explain. 
A. Angles classification, B. Simon's orbital plane, C. Flush terminal plane, D. All of the above
C: Flush terminal plane
Answer: C: Flush terminal plane 
Explanation: None