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
For determining periodontal disease an epidemiological survey is done by using: 
Select and explain. 
A. Gingival index (G.I.), B. Plaque index (P.I.), C. Periodontal index (P.I), D. None of the above
C: Periodontal index (P.I)
Answer: C: Periodontal index (P.I) 
Explanation: None