An electric utility has determined that a new power plant is needed and has decided to build either a natural gas-fired plant or a waste-to-energy plant that would serve as both a trash incinerator and a power plant. Surprisingly, although the waste-to-energy plant would produce roughly three times as much air pollution as the gas-fired plant, environmentalists have come out in unanimous support of this option. Which one of the following, if true, most helps to justify the environmentalists' position? ['In the area where the utility operates, both energy use and the volume of trash produced have increased substantially over the last several years.', 'The waste-to-energy plant would replace an existing trash incinerator that produces much more air pollution than the waste-to-energy plant would.', 'The vast majority of the air pollution in the area where the utility operates is produced by trucks and automobiles.', 'Modern gas-fired power plants produce significantly less pollution than gas-fired power plants that were built several decades ago.']