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
'Care index' with respect to epidemiology of oral disease is 
Select and explain. 
A. Ratio of filled teeth to total teeth with caries experience, B. Ratio of filled teeth to teeth present, C. No. of filled teeth per person, D. Ratio of denture users to non-denture users
A: Ratio of filled teeth to total teeth with caries experience
Answer: A: Ratio of filled teeth to total teeth with caries experience 
Explanation: None