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? ['Because plastics create harmful pollutants when burned, an increasing percentage of the plastics handled by waste management companies are being disposed of in landfills.', 'Although many plastics are recyclable, most of the plastics disposed of by waste management companies are not.', 'An increasing proportion of the paper, glass, and metal cans that waste management companies used to handle is now being recycled.', 'People are more likely to save and reuse plastic containers than containers made of heavier materials like glass or metal.']