PrepTest 129, Section 2, 20. In the past, when there was no highway…

How will the right answer fit in terms of support and conclusion?

Only the right answer will add support for disagreeing with the conclusion, or for the opposite conclusion.

Highlight the main conclusion in the passage, if there is one:

setting the highway speed limit at 90 kph (55 mph) has reduced the highway accident rate by at least 15 percent

[BACKGROUND]. [BACKGROUND]. [SUPPORT]. Thus, [CONCLUSION].

The argument is claiming a cause-and-effect relationship between the speed limit and the “highway accident rate”. The right answer will tell us the speed limit might not be the cause, usually by bringing in an alternative cause for the “15 percent” drop in accidents.

Map the wording of the answers to the wording of the passage:

(A) In the years prior to the introduction…

This answer is happening before the speed limit was enforced, so it should be clear that can’t tell us much about cause-and-effect after the speed limit started.

(B) …accidents in the area occurred on roads with a speed limit of under 80 kph (50 mph).

Cool story, but the argument is about what happens on “highways” only. So info about other “roads” really doesn’t support either side of the cause-and-effect claim the author makes.

(C) …most people typically drive faster than the speed limit.

This is a little tricky. If “most people” are speeding, that could make you think the speed limit isn’t working, which would weaken the author’s argument. The problem is this answer doesn’t tell us whether the speed limit caused fewer people to go that fast. What if literally every single person used to speed? Then the conclusion could still totally work, even if this info is true.

(D) …in the past ten years, drivers are better able to maintain control…

This definitely counts as another possible cause of the drop in accidents. And it maps exactly to the timeframe in the passage, which is a huge green flag that this answer is better than (C), which left out chronology altogether.

(E) …features such as seat belts and airbags…

…keep you from getting seriously hurt, but do nothing to prevent accidents. The argument is only concerned with the “highway accident rate”, so this info is 100% irrelevant.

(D) is the correct answer.

Common pattern/s in this question: On a high difficulty one like this, it’s super valuable to recognize the conclusion is about cause-and-effect. That’s what makes the right answer recognizable, and what keeps you from overthinking it and talking yourself into a wrong answer.