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
Range of OHI is: 
Select and explain. 
A. 0-4, B. 3-Jan, C. 0-6, D. 0-12
D: 0-12
Answer: D: 0-12 
Explanation: The Oral Hygiene Index (OHI) was developed in 1960 by John C. Greene and Jack R. Vermillion to classify and assess oral hygiene status.
To calculate the OHI, the DI and CI are summed: OHI = DI + CI 
The DI and CI values range from 0 to 6.
OHI value ranges from 0 to 12.

Essentials of preventive and community dentistry
Soben Peter
5th edition
page no. 318