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': "Russel's periodontal index scores range from \nSelect and explain. \nA. 0-2, B. 0-4, C. 0-6, D. 0-8", 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]