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?

1. The number of school nurses employed by Renston’s elementary schools has not decreased over the past ten years.

2. Children who are allergic to the chemicals are no more likely than other children to have allergies to other substances.

3. 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.

4. The chemicals are not commonly used as cleaners or pesticides in houses and apartment buildings in Renston.
5. Children attending elementary school do not make up a larger proportion of Renston’s population now than they did ten years ago.

这题我也做错了

我的理解是文中说Elementary school nurses in Renston report that the proportion of schoolchildren,

这个proportion是指患病孩子占学校孩子总数的比例,而不是患病孩子占这个地区总人口的比例,

因为是由Elementary school nurses报道的.

我现在的理解是，原文条件说学校学生中被送到校医院的比例增加了。而C取非意思是：因为学生患病后比以前更喜欢去校医院。直接击中原文要害，所以是C。