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
In index of treatment needs (IOTN), treatment grade 4 indicates 
Select and explain. 
A. Extreme / need treatment, B. Moderate / borderline need, C. Severe / need treatment, D. No need for treatment
C: Severe / need treatment
Answer: C: Severe / need treatment 
Explanation: None