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

Jacob-R on May 1, 2019

Hi @lizaclark95

Good question. Clearly the argument is setting of highway speed -> reduction in highway accident rate.

Answer C tells us that “most people typically drive faster than the speed limit.” But why would that information alone weaken the argument that the setting of a speed has reduced the highway accident rate (given that we know that the highway accident rate has in fact decreased?) I agree with your inference that the change is therefore perhaps due to something else, but this answer doesn’t really provide us with any alternative explanation as to what that “something else” is. In fact, it is entirely consistent with the answer option that most people are now driving 60mph with the setting of highway speed, when they were driving way above that before — and so this answer alone does not “most seriously” weaken the argument even if it weakens it slightly.

Answer D is superior because it gives us that explicit alternative explanation: automobile design which allows for safety in dangerous situations. And Answer D is therefore the one you want.

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