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 category was given by Kingsley 
Select and explain. 
A. Functional oral habits, B. Muscular habits, C. Combined ones, D. All of the above
D: All of the above
Answer: D: All of the above 
Explanation: None