PrepTest 129, Section 1, Question 24
Columnist: The amount of acidic pollutants released into(34 more words not shown)
Each of the following, if(7 more words not shown)
- ASome ecosystems have(16 more words not shown)
- BThe amount of(11 more words not shown)
- CThe current decrease(19 more words not shown)
- DThe effects of(12 more words not shown)
- EThe soils of(20 more words not shown)
Reading the argument
Emitting less pollution sounds encouraging. But why assume that the environmental harm will decrease along with current emissions?
What if pollutants already released remain in the environment for a very long time? Imagine an effect lasting hundreds of years. Reducing new emissions wouldn't immediately remove what has accumulated. We also need to consider whether the decline will continue; a temporary reduction might not support the longer-term expectation.
What we’re looking for
The question asks for the exception. Four answers weaken the prediction of an overall decrease in acid rain's harmful effects, and one does not. The useful weakeners may take different routes, so we shouldn't insist that all four match the persistence problem we first imagined. For each one, ask whether it gives a reason that lower recent emissions might fail to produce less environmental harm.
Working the answers
- ACorrect
These mechanisms reduce the damage acids do to some ecosystems. That doesn't give us a reason to doubt an overall decrease in harm; if anything, it describes protection that could help reduce harm. Because it concerns only some ecosystems, it doesn't prove the columnist's overall prediction. But proving that prediction isn't required here. A is the exception because it does not weaken it.
- B
Acid-neutralizing buffers provide protection against acidity. If fewer buffers are being released too, the environment loses some protection at the same time that acidic emissions decline. Think of both the threat and the defense becoming smaller: the threat's reduction alone doesn't tell us how much damage will result. B undermines the simple inference from fewer acidic pollutants to less harm.
- C
The recent downward trend is expected to end as more countries use coal. That makes it less reasonable to project the past decline forward as a basis for reduced environmental effects. We don't need to assume that emissions instantly return to their old peak; losing the expected continuation of the decrease already weakens the forecast.
- D
This directly supports the persistence concern. If the effects accumulate and are largely independent of current acid rain levels, lowering those current levels may leave substantial damage in place. The accumulated effects, rather than just today's rainfall, can determine the environmental outcome.
- E
Soil minerals had provided protection, but that protection is now exhausted in many ecosystems. Even a smaller amount of acid rain could have a substantial harmful effect on soil that has lost its defenses. This makes reduced emissions a less reliable guide to reduced harm. Unlike A's developing protective mechanisms, E describes protection being lost.
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