PrepTest 155, Section 1, Question 6
In a counterattack on the harmful effects of(87 more words not shown)
If all the statements above(12 more words not shown)
- AIf a lake(15 more words not shown)
- BIn some lakes,(24 more words not shown)
- CUnlimed lakes in(25 more words not shown)
- DLiming can be(18 more words not shown)
- EIf a lake's(19 more words not shown)
Reading the argument
Adding lime can help. Keeping it there is the expensive part. The passage gives us a useful treatment: lime neutralizes acid, prevents some damage, and can help restore lakes already harmed. It doesn't say this fixes every lake. And it doesn't remove the source of the acid rain. Stopping that source might be another approach, but we're only given information about this treatment.
The practical problem is that a lake's water doesn't stay put. As the water is replaced, it carries the lime away. Treatment therefore has to be repeated. If the water turns over more often than once every six months, repeating the treatment costs too much for the lake to qualify.
What we’re looking for
This is a collection of facts, not an argument we need to attack. The question asks for the exception: four answers must follow, and one need not. Rather than inventing a prediction for all five, let's check each against what we've been told.
Working the answers
- A
This must be true. A lake whose water is replaced more often than once every six months is ruled out. A candidate must therefore have water replaced every six months or less often. Be careful with less often: replacement every eight or nine months happens less often than replacement every six months. It doesn't mean every three months.
- B
This must be true. The passage says lakes treated with lime must be treated periodically because replacement water carries the lime away. B applies that requirement to some lakes over the long term. Its limited wording is fine: a statement about some treated lakes can follow from the broader requirement given.
- CCorrect
We aren't told how frequently replaced water affects acid damage in lakes that haven't been treated. The passage connects water replacement with the loss of lime and the resulting treatment expense. C instead compares the vulnerability of untreated lakes. Perhaps fresh water helps; perhaps it doesn't. We'd need information about that relationship before drawing this conclusion.
- D
This follows from the treatment's restorative role. Liming isn't described only as prevention before any harm occurs; it can help restore a lake after acidification has harmed its life. D says treatment can still be effective after losses have occurred. It doesn't claim that lime brings killed organisms back to life.
- E
This must be true. Frequent water replacement means frequent loss of lime and the expense of repeated treatments. The last sentence explicitly rules out lakes with sufficiently rapid turnover because of that cost. E describes the same economic limitation.
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