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 PHP index is designed to \nSelect and explain. \nA. Evaluate plaque and calculus on specific tooth surfaces, B. Score plaque on specific tooth surfaces, C. Scores plaque and gingivitis, D. Scores plaque, calculus, gingivitis', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]