AIM GMAT wrote:Waste management companies, which collect waste for disposal in landfills and incineration plants, report that disposable plastics make up an ever-increasing percentage of the waste they handle. It is clear that attempts to decrease the amount of plastic that people throw away in the garbage are failing.

Which one of the following, if true, most seriously weakens the argument?
(A) Because plastics create harmful pollutants when burned, an increasing percentage of the plastics handled by waste management companies are being disposed of in landfills.

Out of scope since this describes how plastic disposal is maintained by waste management companies.

(B) Although many plastics are recyclable, most of the plastics disposed of by waste management companies are not.

Same as A.

(C) People are more likely to save and reuse plastic containers than containers made of heavier materials like glass or metal.

Out of scope since we are not concerned with the people's utility of containers made from heavier metals or from plastic.

(D) An increasing proportion of the paper, glass, and metal cans that waste management companies used to handle is now being recycled.

CORRECT! since, it is possible that while keeping the amount of plastic thrown by people to be constant, may be other stuff in the garbage is recylced increasing the proportion of plastic in garbage.

(E) While the percentage of products using plastic packaging is increasing, the total amount of plastic being manufactured has remained unchanged
Out of scope, since this point focusses on recycling of plastic.

Hope it helps.