Read the text. Fluoride is a mineral that is added to public drinking water supplies in much of the United States in order to reduce levels of tooth decay. When a tooth is forming, fluoride strengthens the enamel, or outside coating of the teeth. The fluoride mixes with the enamel, making it harder. In addition, when fluoride mixes with saliva, it can protect teeth from sugars, further reducing tooth decay. The Centers for Disease Control (CDC) states that drinking fluoridated water provides additional protection even for people who simply brush with fluoride toothpaste. Reports on the impacts of fluoridated drinking water have concluded that it reduces tooth decay by about twenty-five percent. Which organizational structure does this text primarily use?
