Automobile manufacturers who began two decades ago to design passenger vehicles that were more fuel-efficient faced a dilemma in the fact that the lighter, more efficient vehicles were less safe on high-speed highways. However, the manufacturers avoided this dilemma by producing two types of passenger vehicles: a lighter vehicle for medium-speed, local transportation, and a heavier, safer vehicle for long-distance travel. Since most automobile traffic is local, a net savings in fuel use was achieved with no loss in safety. Which one of the following, if true, most strengthens the argument? ['Most high-speed highways are used by both commercial vehicles and passenger vehicles.', 'Most households whose members do any long- distance driving own at least two passenger vehicles.', 'Some automobile manufacturers designed prototypes for fuel-efficient passenger vehicles more than two decades ago.', 'There are more cars using high-speed highways today than there were two decades ago.']