PrepTest 128, Section 2, Question 3
Agriculture researcher: Because of its slow decomposition, paper(61 more words not shown)
The agriculture researcher's argument is(7 more words not shown)
- Apaper by itself(6 more words not shown)
- Bmulch containing paper(9 more words not shown)
- Cmulch containing paper(9 more words not shown)
- Dmulch containing paper(15 more words not shown)
- Emulch of pure(11 more words not shown)
Reading the argument
Slow decomposition makes paper ineffective? If I were imagining paper as a physical shield against wind or water, I might initially expect a material that lasts longer to protect the soil better. But that isn't the relationship the researcher gives us. We can accept the stated results without inventing our own explanation of how mulch works.
Paper alone is ineffective. A mixture of paper and manure decomposes faster and significantly reduces erosion. So far, that gives us a reason to prefer the mixture to paper.
Then the researcher recommends the mixture over paper or manure alone. Wait—what happens with manure alone? We've been told about paper and about the mixture, but not about that third option. Pure manure might work even better than the mixture. If so, adding ineffective paper could make a useful material less effective.
What we’re looking for
The similar prices don't resolve that missing comparison. For this flaw question, I want the answer pointing out that the researcher hasn't shown the mixture to be better than manure alone.
Working the answers
- A
The argument doesn't need to establish that paper is harmless. Even if paper by itself contributed to erosion, that would give us another reason to reject paper alone. It still wouldn't establish that the mixture works better than manure alone. The missing comparison is the issue, not whether paper's poor performance amounts to no help or actual harm.
- B
We do have evidence for this comparison. Paper alone is described as ineffective, while the mixture significantly decreased erosion in the test plots. B names the comparison the evidence supports, not the comparison the researcher failed to investigate.
- CCorrect
What about using just manure? The argument recommends the mixture over that option without giving us its results. Manure alone could prevent more erosion at roughly the same cost. That possibility leaves the evidence intact while undermining the recommendation.
- D
The recommendation compares the mixture with paper alone and manure alone. It doesn't claim that the mixture beats every possible method of preventing erosion. Another method could be better than all three without deciding which of these three mulches works best.
- E
Nutrients are a different benefit from preventing soil erosion. The argument gives us an erosion-based reason for choosing among the materials. Whether pure manure supplies nutrients that paper doesn't supply fails to identify the missing evidence about how well manure alone controls erosion.
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