GMAT Critical Reasoning (CR) | Re: Exposure to certain chemicals commonly used in elementary

Hi

I do not understand the explanation completely. I could not pick any options and also cannot fathom why the right answer is C. It is given that nurses report higher proportion of children who are being sent but in C it is mentioned that no. of allergic children are not likely to be sent to nurses. Therefore this implies that earlier the number of children sent were more so how can argument assume that as per report the proportion of allergic children sent increased as even with the ratio (no.
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