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': 'After examining a patient for periodontal problem using Russets index you have a meanscore of 3. It indicates: \nSelect and explain. \nA. Established periodontal disease, which is reversible, B. Established periodontal disease that is irreversible, C. Beginning of periodontal disease, D. Terminal periodontal disease', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]