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
The index in which the tooth is divided into 9 segments is 
Select and explain. 
A. Patient hygiene performance index, B. Plaque index of silness and Loe, C. Modified Navy plaque index, D. Glass criteria in estimating dental plaque
C: Modified Navy plaque index
Answer: C: Modified Navy plaque index 
Explanation: None