This is context. It provides background information on the current feasibility of hydrogen-powered cars and sets the stage for the author's argument that the fuel-distribution infrastructure for these cars will likely develop quickly.

This is context. The need to create a fuel infrastructure for hydrogen-powered cars sets the stage for the author's argument that such infrastructure will develop and expand quickly.

This is an unstated premise. The author assumes that, like the rapid development of fuel infrastructure for gas-powered cars, the same will happen for hydrogen-powered cars because the infrastructure needed to support new technologies quickly develops due to consumer demands.

This captures the argument's main conclusion. The stimulus concludes that "this infrastructure"—referring to the fuel infrastructure needed for hydrogen-powered cars—"is likely to appear and grow rapidly," which this answer choice correctly restates.

The stimulus doesn't make this argument. It concludes that consumer demand will drive the growth of hydrogen fuel infrastructure, similar to gasoline, but it doesn't claim that both will have the same level of demand—only that each has enough to spur rapid infrastructure growth.