PrepTest 144, Section 2, Question 9
Two lakes in the Pawpaw mountains, Quapaw and(68 more words not shown)
Which one of the following,(8 more words not shown)
- AHighwater Lake is(13 more words not shown)
- BPrior to the(9 more words not shown)
- CHighwater Lake is(5 more words not shown)
- DSeveral other lakes(12 more words not shown)
- EThere used to(19 more words not shown)
Reading the argument
The fishing ban is a plausible explanation. But what else changed at Quapaw Lake?
A moratorium is a ban. After fishing was banned at Quapaw, its fish population recovered. At Highwater, where there was no ban, the population kept falling. That comparison gives us a reason to investigate whether stopping fishing helped. It doesn't settle the cause.
What we’re looking for
Maybe something else changed at Quapaw around the same time. What if animals that had been eating the fish disappeared? Then the fish population could recover even if fishing wasn't the main problem. For a weakener, I'd look for a reason to doubt that the ban explains the rebound, perhaps evidence of another change at Quapaw.
Working the answers
- A
We would need more to make this comparison useful. Is Highwater actually receiving damaging acid rain, and is Quapaw different in that respect? A says only that Highwater's area is highly susceptible. It doesn't distinguish the lakes or explain Quapaw's recovery. We shouldn't add 'unlike Quapaw' to the answer ourselves.
- BCorrect
This takes a different route from looking for another cause. If practically nobody was fishing at Quapaw before the ban, what did the ban change? Stopping an activity that was barely happening is a much less convincing explanation for a substantial recovery. We still don't know what caused the rebound, but we now have a strong reason to doubt the proposed cause.
- C
A size difference alone doesn't tell us why one fish population recovered while the other declined. We would need a connection between the lakes' sizes and the change in their fish populations. C gives us no such connection.
- D
What happened at those other lakes? Were fishing bans introduced there too? Did some other conditions change? Without that information, their increases don't establish an alternative explanation for Quapaw's rebound. The fact that other populations rose is not enough by itself.
- E
The number of different species is different from the number of fish. A lake could contain fewer species and still have a growing total fish population. This change in variety at Highwater doesn't explain why Quapaw's population recovered or undermine the proposed effect of its ban.
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