Remember to always identify the conclusion of an argument. Here our conclusion is: "...the burden of pollution SUCH OLDER UNITED STATES AUTOMOBILES contribute to the global atmosphere will be gradually reduced over the next decade."
Thus, answer choice (E), which focuses on air pollution from United States automobiles increasing due to the TOTAL NUMBER OF AUTOMOBILES in use increasing, is irrelevant to our argument. We want to choose the answer choice that shows why the burden of pollution from the OLDER United Stated automobiles will not necessarily be reduced over the next decade even though many jurisdictions are requiring that automobiles pass emission-control inspections.
That is why answer choice (C) is correct. It most seriously weakens the argument. Even if old automobiles are being traded in for newer ones in the jurisdictions that require emission-control inspections, if there is a thriving market for used older automobiles in the regions that have no emission-control inspections, then the old automobiles being traded in for new ones will merely be used elsewhere in regions that do not have restrictions. Thus, in this case, the pollution that old United States automobiles contribute to the global atmosphere would not be gradually reduced.
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