In the past, when there was no highway speed limit, the highway accident rate increased yearly, peaking a decade ago....

Jacob-R on January 23, 2019

I’m happy to help. We are looking for the answer that, if true, most seriously weakens the argument. In order to find this answer, let’s first understand what the argument is, and whether it might have any potential flaws.

We have an argument about the reduction in highway accident rates, and that setting the speed limit at 55mph has reduced the rate by at least 15 percent.

Answer B is wrong because it tells us something about “roads” rather than highways. The argument in the passage is all about highway speeds, and highway accident rates, and not just any old road. Precision of language matters enormously for the LSAT!

Answer D on the other hand gives us an alternative explanation for why the highway accident rate has gone down. We learn that thanks to changes in auto design, drivers are better able at maintaining control in dangerous situations. This might mean that the reduction was not simply due to setting highway speeds, and this weakens the argument.

I hope this helps. Please let us know if you have further questions.

Jessica-Killeen on January 31, 2019

Thanks so much

Ravi on January 31, 2019

@Jessica-Killeen, we're happy you found it helpful!