Syavashp wrote:
Why is A incorrect?
The question talks about enforcement of speed limits. The question stem tells us that speed bumps help in reducings speed but the magnitude of the benefit is less than 25%. If in this town, people speed by more than 25%, speed bumps probably won't help slow down cars enough for the speed limit to be met.
Answer Choice B is apparently correct but why is it necessary that ambulances slowing for speed bumps is a bad thing? Speeding through lanes is a continous source of danger and I'd give that preference over the occasional ambulance that is slowed down?
As you say, answer choice (A) suggests that the speed humps may not be sufficient to slow down cars enough to meet the speed limit. So what's wrong with answer choice (A)?
First, notice that the town's explicit goal is to "
reduce traffic speed and thereby enhance safety in residential neighborhoods." Answer choice (A) doesn't cast any doubt on the likelihood that speed humps would slow down traffic. Even if many drivers don't slow down enough to hit the speed limit, a 20-25% fall in traffic speed would count as a reduction.
Also, notice that the question is specifically asking for a "
potentially serious
drawback to the plan." That is, it's not asking for a flaw in the reasoning, but rather a "potential drawback" (i.e. a potentially damaging consequence) of the speed humps. So does slowing down emergency vehicles count as a
potentially serious consequence of the plan?
Well, as you say, maybe slowing down emergency vehicles would be worth it? But the question doesn't ask us to make that kind of complicated judgment. Maybe the speed humps will prevent more damage than they cause? Maybe they won't? But either way, it's fair to say that slowing down emergency vehicles is a "
potentially serious drawback."
So for (B) to be correct, we don't need to conclude that speed humps are ultimately a bad idea. We just need to conclude that slowing down ambulances and firetrucks is a "potentially serious drawback." Since that's a reasonable idea, (B) is correct.
I hope that helps!