PrepTest 105, Section 1, Question 23
Deep tillage is even more deleterious to the(54 more words not shown)
The argument depends on assuming(5 more words not shown)
- ATopsoil erosion does(8 more words not shown)
- BIn deep-tillage farming,(11 more words not shown)
- CTilling by any(10 more words not shown)
- DThe most expensive(10 more words not shown)
- EOn average, topsoil(12 more words not shown)
Reading the argument
“Deleterious” means harmful. But what shows that deep tillage is causing the harm?
Farmers who till deeply are ten times more likely to lose topsoil to erosion than farmers using no-till methods. That's a substantial difference in risk, but the farmers might differ in other ways. Perhaps they plant different crops, or the deep-tillage farms are in places already prone to erosion. Either possibility would make me cautious about assigning the whole difference to the tillage method.
Then the author recommends moving to no-till methods. Even if I accept that deep tillage causes erosion, I'd want to know more about the replacement. Could those other aeration techniques cause problems of their own? How serious is the erosion being avoided, and what tradeoffs come with the change? Showing a drawback of the current approach doesn't by itself settle what should replace it.
What we’re looking for
The question asks for an assumption the argument needs. My first predictions would defend against those concerns: connect the erosion to deep tillage, or establish that the proposed replacement is a workable improvement. Let's see which gap the answers address.
Working the answers
- A
Farmers could respond to erosion by wanting to till more deeply, even if doing so would be harmful and they should change methods. A statement about what they want is not required for the author's recommendation about what they should do. Nor does A establish what actually caused the measured difference in erosion.
- B
The argument compares deep tillage with no tillage. It doesn't require a steadily increasing risk with every increase in depth. All methods classified as deep tillage could carry the same erosion risk, and the comparison could still support the author's concern. B adds a within-category pattern the reasoning does not need.
- CCorrect
This exposes another gap: what about shallower tillage? The argument moves straight from a problem with deep tillage to recommending no tillage. Perhaps moderate or light tillage would provide the needed aeration without the same erosion problem. Neither side of the stated comparison tells us what happens in that middle category.
C rules out that alternative by saying that other forms of tillage are not viable options. The author needs that exclusion to justify treating no-till methods as the replacement without considering a less drastic change. This wasn't the gap my initial prediction focused on, but it directly challenges the move from the evidence to the recommendation.
Notice that C excludes other tilling methods. It does not exclude no-till methods or the other aeration techniques the conclusion recommends.
- D
We don't need a ranking of the most expensive farming methods to make this argument. Costs could matter in evaluating a farming recommendation, but this particular statement about which methods are most expensive is not required by the erosion-based reasoning. It supplies neither the causal connection nor a reason to rule out other workable alternatives.
- E
No-till soil doesn't have to be more aerated. Equal aeration might be sufficient, or even somewhat less aeration might be an acceptable tradeoff for avoiding erosion. The author recommends a way to reduce harm, not necessarily a way to maximize aeration. E demands an additional advantage the argument doesn't require.
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