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': 'The index in which the tooth is divided into 9 segments is \nSelect and explain. \nA. Patient hygiene performance index, B. Plaque index of silness and Loe, C. Modified Navy plaque index, D. Glass criteria in estimating dental plaque', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]