Critical Reasoning

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.

Can you please explain how the OA isC

known: no. of children sent for treatment has increased.
conclusion: either more exposure to chemicals or more sensitive to chemicals.

a)no. of school nurses is irrelevant
b) allergies to other substances is irrelevant
c) conclusion is that children are more exposed or more sensitive but maybe 10 years ago, children were not sent to nurses even if they had allergic reactions. Thus for conclusion to remain valid, likeliness that children are sent to nurses should remain same

d) even if chemicals are used in cleaners and pesticides, it supports the conclusion that children are more exposed now
e) irrelevant

why not D, D is more specific than C. Please clarify!

Hi Cans,
1 doubt.

conclusion is that children are more exposed or more sensitive but maybe 10 years ago, Agreed.
children were not sent to nurses even if they had allergic reactions.
For this part to be true they must be suffering from allergies which might not be happening at that point of time.
Thus for conclusion to remain valid, likeliness that children are sent to nurses should remain same

gmatblood wrote:why not D, D is more specific than C. Please clarify!

Hi

It is not D because IMO, the segment from the sentence "either Renston's schoolchildren have been exposed to greater quantities of the chemicals" covers all places, incl houses,apartments etc. SO no need to assume that again.

The premise should be not explicitely mentioned. It should be hidden!