The following question has two parts. First, answer part A. Then, answer part B.

Part A:

Which of the following BEST describes the purpose of the presentation?
A
to make the claim that fluoride in water supplies is no longer needed

B
to point out the benefits of adding fluoride to city water supplies

C
to introduce reasons that adding fluoride to drinking water is controversial

D
to explain why public health officials first added fluoride to drinking water

Part B:

Which sentence from the presentation BEST supports your answer in part A?
A
In 1945, some cities in the United States began adding fluoride, a chemical that protects teeth from cavities, to their drinking water.

B
Since 1945, the country's dental health has gotten much better, and we are also more aware of how important good dental care is.

C
Most people prefer having fluoride in their water, but some have complained to their city governments about it.

D
Experts agree that fluoride added to city water has really improved the health of people's teeth.