ziyuenlau wrote:aspirant2011 wrote:Exposure to certain chemicals commonly used in elementary schools as cleaners or pesticides causes allergic reactions in some children. Elementary school nurses in Renston report that the proportion of schoolchildren sent to them for treatment of allergic reactions to those chemicals has increased significantly over the past ten years. Therefore, either Renston's schoolchildren have been exposed to greater quantities of the chemicals, or they are more sensitive to them than schoolchildren were ten years ago.
Which of the following is an assumption on which the argument depends?
A. The number of school nurses employed by Renston's elementary schools has not decreased over the past ten years.
B. Children who are allergic to the chemicals are no more likely than other children to have allergies to other substances.
C. Children who have allergic reactions to the chemicals are not more likely to be sent to a school nurse now than they were ten years ago.
D. The chemicals are not commonly used as cleaners or pesticides in houses and apartment buildings in Renston.
E. Children attending elementary school do not make up a larger proportion of Renston's population now than they did ten years ago.
CONCLUSION : Therefore, EITHER Renston's schoolchildren have been exposed to greater quantities of the chemicals, OR they are more sensitive to them than schoolchildren were ten years ago.
(C) Children who have allergic reactions to the chemicals are NOT MORE LIKELY to be sent to a school nurse now THAN they were ten years ago.
Upon negating the answer choice (C), I found out that (C) does NOT weaken the conclusion but instead similar to the author's conclusion. Could someone help to elaborate in details?
The negation of
C:
Children who have allergic reactions to the chemicals ARE more likely to be sent to a school nurse now than they were ten years ago.
If more kids are getting sent to the nurse for allergic reactions, there are two possible explanations. 1: more kids are having allergic reactions. 2: if a student has an allergic reaction, that student is more likely to be sent to the nurse. In scenario 2, there aren't more cases of allergies, but rather, the school is doing a better job of diagnosing them.
The negation of
C gives us scenario 2. If students are more likely to be sent to the nurse after having an allergic reaction, it suggests that, in the past, many students were having reactions, but these reactions weren't being reported. So the increase in the reported number of incidents isn't evidence that more kids are getting exposed to chemicals, but rather, evidence that when the kids are exposed, that exposure is more likely to be reported. Because the argument asserts that more kids are, in fact,
having reactions, the negation of
C undermines the argument, so we know it's the correct answer.
