Most water companies in the United States add fluoride to tap water to

OFFICIAL EXPLANATION

The dentists argue that adding fluoride to tap water lulls people into a false sense of dental security because they rely too heavily on the fluoride to do work they should do for themselves. The dentists rely on the assumption that people are aware that fluoride is added to the water. The correct answer will weaken the conclusion by contradicting this assumption.

(A) The ingredients in commercially available dental care products are irrelevant to the dentists’ argument about whether adding fluoride to tap water is ultimately beneficial.

(B) CORRECT. If most Americans are not aware that fluoride is added to tap water, then they must not be relying on it to protect their teeth. Poor dental hygiene might just be due to laziness or apathy, and this behavior would remain unchanged even if the water companies stopped adding fluoride to tap water. If anything, tooth decay would be likely to increase, since people would no longer get any protection from the tap water.

(C) The most effective means of controlling tooth decay, whether by annual dental exams or some other means, is irrelevant to the dentists’ argument about whether adding fluoride to tap water is ultimately beneficial.

(D) How the United States ranks in terms of tooth decay is irrelevant to the dentists’ argument about whether adding fluoride to tap water is ultimately beneficial.

(E) The current dental hygiene routine of most Americans is irrelevant to the dentists’ argument about whether adding fluoride to tap water is ultimately beneficial.