Each of the following, if true,

Answer choices

1. A

   Correct65% picked this

   The amount of fruit that an orchard can potentially produce depends in part on how many mature trees it contains, and the number of

   Why this is right

   This has no effect on the argument. We're measuring the effectiveness of these pesticides in terms of proportion lost to insects, not number. So it makes no difference if the raw number of pears is getting higher or lower. We're looking at data that says, "during the previous 3 years of using the old pesticide, we lost 13% of our pears to insects. During the 3 years of the new pesticide, we only lost 8% of our pears."

   Skill tested: Weaken · how this choice captures the argument's function is the move to repeat next time.

   65%
2. B

   Weakens: alternative explanation9% picked this

   During the past five years, the farmers of the District 10 Farmers’ Cooperative have been gradually implementing a variety of insect- abatement programs, and

   This offers a different explanation for why a lower proportion of pears have been lost to insects recently: it's not because of the new pesticide, it's because of the insect-abatement programs that have been successful. We might worry that the timelines don't match perfectly. We want to explain why the last three years have been better than the previous three years. This talks about something that transcends both three year period. However, it has been gradually implemented over five years. Thus, we'd expect there to be less effect from it 5 years ago, slightly more 4 years ago, and then increasingly more effect during these past 3 years. The timelines don't have to match perfectly. If we think this program has affected the last 3 years more than it's affected the prior 3 years, then it can explain why the last 3 years look better than the prior 3 years.

   9%
3. C

   Weakens: alternative explanation6% picked this

   Over the past five years, one of the several species of birds that typically prey on the insects that feed on pears has gradually

   This offers a different explanation for why a lower proportion of pears have been lost to insects recently: it's not because the new pesticide is doing a better job killing insects; it's because there are more birds in our area who prey on these insects. Just like (B), the timelines don't match perfectly, but again this is a change that has gradually shifted over the past five years. Thus, we'd expect there to be more effect in the past 3 years than in the 3 years prior to that.

   6%
4. D

   Weakens: alternative explanation7% picked this

   Some of the species of insects in District 10 that infest pear trees are water breeders, and the reservoirs and marshlands in this district

   This offers a different explanation for why a lower proportion of pears have been lost to insects recently: it's not because the new pesticide is better at killing insects, it's because some of the insects haven't been able to breed (they breed in water and over the past three years the wet habitats have rapidly shrunk). Not as much wetlands, not as many water breeding insects being born, not as many insects to eat our pears.

   7%
5. E

   Weakens: plausibility of explanation13% picked this

   The effects of certain pesticides, including the pesticide that had formerly been used in District 10, are cumulative and persist for several years after

   This doesn't quite offer a different explanation for why a lower proportion of pears have been lost to insects recently. But it makes it implausible to think that the change is because the new pesticide is better than the old one. After all, according to this answer, the old pesticide's effects are still felt during this previous 3 year stretch. We can't start measuring the effectiveness of the new pesticide until the old one's effects have worn off, and the old pesticide's effects are still going strong during the last few years (we stopped using it 3 years ago, but the effects persist for several years after it stops being applied).

   13%