PrepTest 141, Section 4, Question 26
Farmer: Crops genetically engineered to produce toxins that(40 more words not shown)
Which one of the following(7 more words not shown)
- AUse of the(27 more words not shown)
- BWildlife populations that(28 more words not shown)
- CCrops that have(16 more words not shown)
- DUse of crops(27 more words not shown)
- EIf a wider(45 more words not shown)
Reading the argument
Avoiding a harmful spray sounds good for wildlife. But what do the replacement crops do to the same ecosystem?
The crops produce their own insect-resisting toxins, so they don't need the insecticide spraying the farmer identifies as harmful. That removes one reason for harm. It doesn't automatically establish that the replacement is better overall.
For example, suppose insects lose an important food source around these crops. That could affect rodents that eat the insects, and then animals that eat the rodents. This is a possible chain of effects to consider, not a fact about these crops. It illustrates why changing how pests are controlled might create a different problem for wildlife.
What we’re looking for
The farmer predicts that wider use will help wildlife recover. For this necessary-assumption question, my first guess is something protecting against that food-chain concern. Perhaps the affected insects aren't an important food source for the wildlife, or perhaps the change won't trigger the harmful chain of effects. We need an assumption the farmer relies on, so let's test whether the answers address a gap in the recovery prediction.
Working the answers
- ACorrect
This answers the concern at a broader level than the initial food-chain prediction. The argument depends on the replacement causing less harm to wildlife. If using the engineered crops instead of sprayed crops harmed wildlife just as much or more, avoiding the spraying wouldn't support the predicted recovery. A addresses the broader comparison behind the food-chain concern, without requiring us to prove that every possible side effect is absent.
- B
Recovery needn't result from even the slightest reduction in spraying. Perhaps a substantial reduction is needed, and wider use of these crops would provide it. The farmer's proposal doesn't depend on a tiny decrease being enough to make damaged populations likely to recover.
- C
Not needing a spray doesn't mean no farmer ever uses one. More importantly, the proposed benefit doesn't require spraying to disappear entirely. For example, a change from 100 sprayings to one could be a major reduction even though 'never sprayed' would be false. Those are hypothetical numbers, but they show why C demands more than the argument needs.
- D
The conclusion concerns wildlife recovery, not whether the change costs farmers less or the same amount. The crops could be more expensive and still be less harmful to wildlife. Cost might affect other decisions, but this environmental prediction doesn't require equal or lower expense.
- E
The farmer doesn't need to establish that preventing spraying is the only way these crops could help wildlife. Other benefits could contribute too. Nor does the argument say the harmful spraying was ineffective at controlling pests. E adds both an exclusive explanation and a claim about ineffectiveness that the reasoning doesn't require.
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