The success of fluoride in combating dental decay is well established

1. ​​​​In the passage, the author is primarily concerned with

The first paragraph describes the problems with excess fluorine, whereas the second paragraph issues a note of caution against indiscriminate usage of fluorine composed substances. This thought is perfectly described in (D)

(D) describing and cautioning

Hence, (D) is the right answer choice.

2. ​The passage suggests that it would be easier to calculate fluoride intake from food if

In the first paragraph, "variation in diets'' and ''variations in fluorine concentrations'' are cited as reasons why it is difficult to calculate fluorine intake from food. Hence, (B) represents a possible correction that would make it easier for us to determine fluoride intake from food.

(B) individual eating habits were more uniform

Hence, (B) is the right answer choice.

3. ​​​​​One function of the second paragraph of the passage is to


The answer to this question lies in the first sentence of the second paragraph "Some important questions remain". Only (D) describes this thought perfectly

(D) indicate that necessary knowledge of fluoride remains incomplete
hence, (D) is the right answer choice.

4. ​​​​​​​​​The passage suggests which of the following about the effect of fluoride on humans?


The passage mentions that if humans consumer over 4 milligrams of fluorine everyday for several years, then humans may suffer from skeletal fluorosis, a well-defined skeletal disorder.

(E) An intake of slightly more than 4 milligrams for only a few months is not likely to be life-threatening. - according to the information in the passage, if humans consume over 4 milligrams of fluorine everyday for several years, then humans may suffer from skeletal fluorosis, a well-defined skeletal disorder. From this statement, we can reasonably infer that if humans consume more than 4 milligrams of fluorine everyday for only a few months, then it is likely that these humans may not suffer from any life-threatening issues.

Hence, (E) is the right answer choice.