题目选项分析

Ethanol is a derivative of corn and other grains. When burned as fuel, it emits significantly lower levels of carbon monoxide, a major atmospheric pollutant, than does gasoline. For that reason, environmentalists claim that ethanol is a better source of energy than gasoline.

Which of the following, if true, most strongly supports the environmentalists' claim?

【选项】Available supplies of corn are sufficient to supply several years' worth of ethanol.