22 An epidemiologic study evaluates the rate of dental caries and tooth abscesses among children living in communitieswithin a metropolitan area. Investigators discover that the rate is high among children living in an upper middle class community, but low in children living in a community below the poverty level. The levels of trace elements in the water supplies for those communities are measured. A higher level of which of the following minerals in the water is most likely to be associated with a lower rate of dental decay among the children living in the poor community? (A) Zinc (B) lodine (C) Selenium (D) Fluoride (E) Copper