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 following is a composite index? 
Select and explain. 
A. DMFT, B. OHI, C. Russel's index, D. OHI-S
C: Russel's index
Answer: C: Russel's index 
Explanation: None