Adental student wants to test if fluoride is an effective additive against tooth decay. the student studies tooth decay in a population of people who live in neighborhoods supplied with fluoridated water. this student would like to ask whether access to fluoridated water prevents tooth decay. what would be an effective control group to ask this question?

Individuals with access to water with no fluoride added.

Explanation:

When we want to do an experiment we must establish which will be the experimental group (one where the factor tested in the experiment is applied) and a control group (one that was set exactly the same as the experimental group but the factor tested in the experiment was not applied). In the case shown in the question above, the student wants to develop an experiment that tests whether fluoridated water is effective in preventing tooth decay.

This student's experimental group is a group of people who consume water with the addition of fluor (factor tested in the experiment) in their composition, whereas their control group will be a group of people who do not consume water with the addition of fluor in their composition.