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
[{'content': 'CPITN index is used to assess: \nSelect and explain. \nA. The degree of periodontal destruction, B. The amount of calculus present, C. The treatment needs, D. The degree of inflammation of the gingival tissues', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]