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
CPITN index is used to assess: 
Select and explain. 
A. The degree of periodontal destruction, B. The amount of calculus present, C. The treatment needs, D. The degree of inflammation of the gingival tissues
C: The treatment needs
Answer: C: The treatment needs 
Explanation: None