题目选项分析

Though the law will require emissions testing of all diesel vehicles, from tractor trailers to excursion buses, it will have no effect on sport utility vehicles, almost all of which are gasoline powered and therefore not subject to emissions-control standards as stringent as those for diesel-powered vehicles.

Though the law will require emissions testing of all diesel vehicles, from tractor trailers to excursion buses, it will have no effect on sport utility vehicles, almost all of which are gasoline powered, and therefore not subjected to emissions-control standards that are as stringent as those of diesel-powered vehicles.