PrepTest 148, Section 3, Question 2
Archaeologist: For 2,000 years the ancient Sumerians depended(61 more words not shown)
Which one of the following,(7 more words not shown)
- AMost modern civilizations(11 more words not shown)
- BFactors unrelated to(15 more words not shown)
- CMany modern farmers(16 more words not shown)
- DMany modern civilizations(11 more words not shown)
- EThe soil of(18 more words not shown)
Reading the argument
Have modern farmers learned how to prevent that buildup?
The Sumerians' problem makes sense as described. Irrigation water evaporated, leaving salts and other impurities behind. Over time, those substances reached levels that the crops couldn't tolerate. Losing the agriculture that fed the civilization could explain its collapse.
What we’re looking for
But the modern prediction needs another step. Relying on irrigation doesn't necessarily mean using it in a way that creates the same soil problem. Perhaps farmers now have a way to remove the impurities or prevent them from accumulating. We don't need to know how such a technique works to see why its existence would matter. For a weakener, I'd look for that relevant change: modern irrigation can avoid the problem that ruined the ancient soil.
Working the answers
- A
This says heavy reliance on irrigation is widespread. But the conclusion already concerns civilizations that rely heavily on it. Learning that many civilizations belong to that group doesn't show the prediction about the group is wrong. Their dependence could make the concern more pressing; it doesn't solve the soil problem.
- B
Another problem might eventually have brought Sumerian civilization down. That doesn't rule out the stated agricultural collapse or show that modern farmers can avoid the proposed irrigation problem. A civilization could face more than one potential threat. We need a reason the particular lesson the author draws from irrigation doesn't carry over.
- CCorrect
These farmers avoid the very buildup used to predict disaster. That makes modern irrigation importantly different from the ancient practice in the argument: the water can support farming without leaving the soil on the same path toward toxic concentrations. C doesn't prove every modern civilization is safe or that all agricultural problems have been solved. It undermines the assumption that relying on irrigation today is likely to produce the Sumerians' result.
- D
Those civilizations fall outside the prediction. The author only forecasts this fate for civilizations that continue to rely heavily on irrigation. There could be many other civilizations that don't rely on it, and the author's claim about the dependent ones could still be right. We need to challenge what happens within the relevant group.
- E
Some impurities at the start are compatible with irrigation later raising them to toxic levels. A small initial amount needn't prevent crops from growing. What matters is the later accumulation, and E doesn't show that irrigation wasn't responsible for that buildup or that modern irrigation will avoid it.
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