#18 - In grasslands near the Namib Desert there are “fairy

[Dave Killoran]

The key to the entire problem is in the stimulus (as always!). In particular the scientists' hypothesis is quite pointed: "it is the burrowing activities of these termites that cause the circles to form" (italics added). The question stem then asks you to support this hypothesis, and the key to correctly choosing (A) is to realize it is the only answer that addresses "burrowing." This is critical because most students head into the answers simply trying to prove that termites and fairy circles are linked; that's not enough here, and you need an answer that links burrowing with the circles.

Answer choice (A): This is the correct answer. Note that the discussion of damage here centers on the roots, which helps support the idea that the burrowing activity is connected to these circles.

The elements we have present—burrowing and lack of vegetation in the circles per the stimulus, and new circles with plants dying just at the roots in (A)—look to me (and the test makers) like a viable connection. But again, you aren't looking to prove the argument or even make it extremely strong; you just need to support it in some way. For me at least, I believe the connection is strong enough to qualify as more than just compatible. It adds another piece that would be an effect of the burrowing, and this adds a piece of support to it.

Answer choice (B): It's not a likely scenario that climate is causing unique circles to form in the desert, and to think this rules out an alternate cause is something that LSAC would say is too tenuous of a connection. Even interpreted in the best possible light, this answer would require further assumptions (such as the grasses inside the circles are for some unknown reason less able to survive these conditions than the grasses outside the circles) and be far more indirect than answer choice (A)'s direct support of the termite burrowing explanation.

Answer choice (C). This answer, like (B), would at best make an indirect case for supporting the argument. And, like (B) it requires further assumptions because it simply discusses relative water content, but that is no indication that the water content inside the fairy circles was ever insufficient (meaning, a "higher content" doesn't mean that previous the water content was too low to support grasses).

The argument that LSAC would make here is that (A) links the direct cause (burrowing) to what is occurring; (B) and (C) require further assumptions to properly play the role of knocking out alternate causes.

[AWash180]

Could someone explain the differences between answers A and E and why A is correct?

Thank you!

[James Finch]

Hi A. Wash,

As a Strengthen question, we need to make the conclusion more likely to be true. That conclusion is that sand termites cause the fairy circles with their burrowing. (A) would work to strengthen this connection by helping to eliminate possible alternate causes (like animals eating the grass in circular patterns) and help narrow it down to root damage as the cause, which would fit with sand termite burrowing.

(E) is incorrect because it doesn't affect the link between burrowing sand termites and the fairy circles, but only would provide evidence of the presence of sand termites. But we already know sand termites are in the fairy circles, so this is irrelevant information to the argument in the stimulus.

Hope this clears things up!

[Lsat180Please]

Hi can you please discuss why A is better than B? I thought B ruled out an alternate cause by ruling out the idea that fairy circles are forming from climatic conditions.
Thank you!

[Dave Killoran]

Hi can you please discuss why A is better than B? I thought B ruled out an alternate cause by ruling out the idea that fairy circles are forming from climatic conditions.
Thank you!

I happen to be a huge fan of this question, so let's break it down and see why this ended up being so difficult for most test takers.

The key to the entire problem is in the stimulus (as always!). In particular the scientists' hypothesis is quite pointed: "it is the burrowing activities of these termites that cause the circles to form" (italics added). The question stem then asks you to support this hypothesis, and the key to correctly choosing (A) is to realize it is the only answer that addresses "burrowing." This is critical because most students head into the answers simply trying to prove that termites and fairy circles are linked; that's not enough here, and you need an answer that links burrowing with the circles.

Answer choice (A): Note that the discussion of damage here centers on the roots, which helps support the idea that the burrowing activity is connected to these circles.

Answer choice (B): It's not a likely scenario that climate is causing unique circles to form in the desert, and to think this rules out an alternate cause is something that LSAC would say is too tenuous of a connection. Even interpreted in the best possible light, this answer would require further assumptions (such as the grasses inside the circles are for some unknown reason less able to survive these conditions than the grasses outside the circles) and be far more indirect than answer choice (A)'s direct support of the termite burrowing explanation.

Thanks!

[jayzbrisk]

Doesn't answer choice C support the hypothesis by defending against a potential weaker i.e. that there was a lack of water in the fairy circles and that is the cause instead?

Also doesn't answer choice A just give us a scenario which is compatible with the hypothesis as opposed to supporting it? Maybe there can be other reasons why the plants would be damaged at the roots and therefore we have no support?

Hi can you please discuss why A is better than B? I thought B ruled out an alternate cause by ruling out the idea that fairy circles are forming from climatic conditions.
Thank you!

I happen to be a huge fan of this question, so let's break it down and see why this ended up being so difficult for most test takers.

The key to the entire problem is in the stimulus (as always!). In particular the scientists' hypothesis is quite pointed: "it is the burrowing activities of these termites that cause the circles to form" (italics added). The question stem then asks you to support this hypothesis, and the key to correctly choosing (A) is to realize it is the only answer that addresses "burrowing." This is critical because most students head into the answers simply trying to prove that termites and fairy circles are linked; that's not enough here, and you need an answer that links burrowing with the circles.

Answer choice (A): Note that the discussion of damage here centers on the roots, which helps support the idea that the burrowing activity is connected to these circles.

Answer choice (B): It's not a likely scenario that climate is causing unique circles to form in the desert, and to think this rules out an alternate cause is something that LSAC would say is too tenuous of a connection. Even interpreted in the best possible light, this answer would require further assumptions (such as the grasses inside the circles are for some unknown reason less able to survive these conditions than the grasses outside the circles) and be far more indirect than answer choice (A)'s direct support of the termite burrowing explanation.

Thanks!

[Dave Killoran]

Hi Jay,

Thanks for the question! As far as (A), this is always about how the test makers see the answer, and I think they have a good case for (A) making sense as far as connecting elements and supporting the argument. The elements we have present—burrowing and lack of vegetation in the circles per the stimulus, and new circles with plants dying just at the roots in (A)—look to me (and the test makers) like a viable connection. But again, you aren't looking to prove the argument or even make it extremely strong; you just need to support it in some way. for me at least, I believe the connection is strong enough to qualify as more than just compatible. It adds another piece that would be an effect of the burrowing, and this adds a piece of support to it.

Let's look at answer choice (C). This answer, like (B), would at best make an indirect case for supporting the argument. And, like (B) it requires further assumptions because it simply discusses relative water content, but that is no indication that the water content inside the fairy circles was ever insufficient (meaning, a "higher content" doesn't mean that previous the water content was too low to support grasses).

The argument that LSAC would make here is that (A) links the direct cause (burrowing) to what is occurring; (B) and (C) require further assumptions to properly play the role of knocking out alternate causes.

Please let me know if that helps. Thanks!

[lanereuden]

Is this a fair analogy?


If you have a big group of students (grasslands) and one group of students (a circular area of that land) that does not do well (has virtually not vegetation in it), and you are looking to explain why this group of students didn’t do well, you would not rule out, as an explanation, that everyone else (most of the grassland) is doing really well and able to withstand anything. Why wouldn’t you rule this out? Because it’s too obvious and secondly,
it does not give you any insight into why that group of students is not performing (that patch of grass is acting strange/in the shape of a circle)....or is parallel argument oversimplifying things/lacking an important idea ?

[Brook Miscoski]

lanereuden,

I wouldn't make that analogy. I think that there's some value in trying to formulate parallel arguments, but the best value is in understanding how to use technique to efficiently get the correct answer. In this case, scientists proposed that burrowing caused the fairy circles:

(A) Roots involve things that happen underground. Good choice.
(B) Eliminating drought as a cause doesn't make sense because the drought is affecting everything in and around the circle, so it doesn't explain the difference. This choice doesn't indicate that there was previously a different kind of grass in the circles, and the stimulus was about all vegetation.
(C) This attacks the scientist's hypothesis by suggesting that a difference in available water is causing the phenomenon. Our goal is to strengthen.
(D) This doesn't indicate why they form, so it's irrelevant.
(E) This doesn't indicate why they form (the animals are living in and around the circles, so it's not a difference), so it's irrelevant.

The explanations above all hit these points from the same or similar perspectives--and that's what you want to model.

If I were going to make an analogy like yours, I would do it as follows:

There is a University. The students who live in some of the dormitories do noticeably worse than the University average. The Student Council has hypothesized that increased traffic noise from the several roads is preventing proper sleep and study, resulting in this lower performance.

(A) The students at the affected dormitories are often treated for sleep deprivation.
(B) The women in other dormitories are able to perform well even with a heavy course load.
(C) The affected dormitories are newer and have more luxurious recreational amenities than the other dormitories have.
(D) The affected dormitories are close together.
(E) There are a plethora of nightclubs and bars near campus.

[shawnhaq]

Hi Dave,

I was conflicted between answer choices A and E, both of which I viewed as supporting the hypothesis of "burrowing" specifically.

If E is true and species of animals that feed on the sand termites are often often found living near fairy circles then it would logically follow (at least to me) that the sand termites may be burrowing to hide from their predators near the fairy circles. If that's a reasonable line of logic, then wouldn't answer choice E also provide additional reasoning to support the hypothesis of burrowing?

Given my interpretation of the question and answer choices A and E I am having a hard time trying to determine why A is a better answer than E. I'd appreciate any additional insight you have on this.


Thanks for all that you do.