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 teeth are not excluded from the scoring in Simplified Oral Hygiene Index (OHI-S)? 
Select and explain. 
A. Natural teeth with full crown restorations, B. Surfaces reduced in height by caries, C. Traumatized teeth, D. Functional third molars
D: Functional third molars
Answer: D: Functional third molars 
Explanation: The Simplified Oral Hygiene Index (OHI-S) was developed in 1964 by John C. Greene and Jack R. Vermillion. 
Natural teeth with full crown restorations and surfaces reduced in height by caries or trauma are not scored. Third molars are  included only if they are functional