B and C are clearly different. B is not relevant to the original argument. C, on the other hand, is an assumption of the original argument. Try deny C, we get "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 so, this could have caused most of the reported increase by nurses, and the original argument that "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" would fall apart. So, C is an assuptiond the best answer. |