PrepTest 114, Section 4, Question 14
Reducing speed limits neither saves lives nor protects(34 more words not shown)
The argument's reasoning is flawed(3 more words not shown)
- Aneglects the fact(7 more words not shown)
- Bignores the possibility(12 more words not shown)
- Cfails to consider(22 more words not shown)
- Dpresumes, without providing(20 more words not shown)
- Epresumes, without providing(20 more words not shown)
Reading the argument
More time driving doesn't automatically mean more pollution—or more deaths.
The safety claim makes me pause first. A low-speed collision and a high-speed collision needn't be equally serious. Imagine a minor parking-lot scrape compared with a severe highway crash. Even if slower driving left people exposed to possible collisions for longer, the consequences of those collisions might change. Counting opportunities to crash doesn't by itself settle how many lives are lost.
The environmental claim has a similar problem. Time is only part of the calculation. What if the car releases less exhaust per minute when driven more slowly?
Imagine a trip taking twice as long but producing only a quarter as much exhaust each minute. Total emissions would be half as large. Those are hypothetical numbers, not a claim about any particular speed or car.
What we’re looking for
For the flaw, I'd look for one of these missing comparisons. The author treats time on the road as enough to settle the overall outcomes without accounting for how much pollution or harm that time produces.
Working the answers
- A
Some drivers ignoring the limit doesn't show what happens among drivers who obey it or how the overall outcome changes. The argument's central problem remains even if everyone complies: longer driving time alone doesn't establish either the total emissions or the number of deaths. A doesn't identify that unsupported step.
- B
The conclusion is specifically about lives and the environment. Some additional benefit could exist without contradicting the claim that the limits fail to provide those two benefits. We aren't evaluating whether reducing speed limits is good in every respect. B expands the question beyond the effects the author addresses.
- C
More cars being on the road at once might add a concern about congestion or exposure to collisions. It doesn't expose why the author's reasoning fails to establish the conclusion. In particular, it still wouldn't tell us the emissions rate or the seriousness of collisions. An additional possible downside isn't the missing comparison we need.
- DCorrect
This identifies the emissions assumption. The author gives longer travel time as the reason lower speeds don't protect the environment, treating time as the main determinant of a trip's total exhaust.
But emissions per unit of time could change with speed. Our numerical example shows why the longer trip could produce less pollution despite lasting longer. D doesn't need to address the separate safety claim as well. It identifies a real unsupported assumption in one part of the argument.
- E
This makes a stronger claim than the author needs: a significant collision risk requires a lot of time on the road. The author could think even a short trip has a significant risk while claiming that a longer trip increases it. E turns a proposed relationship between more time and more exposure into a requirement that only long trips carry significant risk. That isn't the mistake the passage makes.
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