Politician: Hybrid cars use significantly less fuel per kilometer than nonhybrids. And fuel produces air pollution, which contributes to a number of environmental problems. Motorists can save money by driving cars that are more fuel efficient, and they will be encouraged to drive hybrid cars if we make them aware of that fact. Ttherefore, we can help reduce the total amount of pollution emitted by cars in this country by highlighting this advantage of hybrid cars. Which of the following, if true, would most indicate a vulnerability of the politician's argument? ['People with more fuel-efficient cars typically drive more than do those with less fuel-efficient cars.', 'Hybrid cars have already begun to gain popularity.', 'Not all air pollution originates from automobiles.', 'The future cost of gasoline and other fuel cannot be predicted with absolute precision or certainty.']