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
Score of 8 on the Russel periodontal index shows: 
Select and explain. 
A. Irreversible terminal disease, B. Established destructive periodontal disease, C. Beginning destructive periodontal disease, D. Advanced destructive periodontal disease with loss of masticatory function
D: Advanced destructive periodontal disease with loss of masticatory function
Answer: D: Advanced destructive periodontal disease with loss of masticatory function 
Explanation: None