In grasslands near the Namib Desert there are fairy circleslarge

Question

In grasslands near the Namib Desert there are “fairy circles”—large, circular patches that are entirely devoid of vegetation. Since sand termite colonies were found in every fairy circle they investigated, scientists hypothesize that it is the burrowing activities of these termites that cause the circles to form.

Which one of the following, if true, most supports the scientists’ hypothesis?

(A) Dying grass plants within newly forming fairy circles are damaged only at the roots.
(B) The grasses that grow around fairy circles are able to survive even the harshest and most prolonged droughts in the region.
(C) The soil in fairy circles typically has higher water content than the soil in areas immediately outside the circles.
(D) Fairy circles tend to form in areas that already have numerous other fairy circles.
(E) Species of animals that feed on sand termites are often found living near fairy circles.

Rickooreoisb · Answer

Conclusion of the argument is - scientists hypothesize that it is the burrowing activities of these termites that cause the circles to form.

Approach for strengthen is that it should help conclusion. Option A does not mention that the termite caused this and hence I rejected. Where I am missing

I selected option E because termites to hide from predator will burrow and hence there is difference in the area. I understand that this does not neccessarily mean there is no vegetation but A does not have termite causing it so I didn't even bother looking at it

I understood the learning from this question, but the approach I used that if the conclusion is not directly linked, I should eliminate the option—will now be difficult to apply. In the exam, if I see a reason to eliminate (A), and I have already eliminated (B), (C), and (D), then when I see termites mentioned in (E) with even a remote link to predators, burrowing, and damage, I will be inclined to choose it. I want to learn how to refine my exam approach as well.

AdarshSambare · Answer

The scientists’ hypothesis: sand termites’ burrowing causes fairy circles.
We want evidence that directly links termites’ activity to killing grass.
(A) Dying grass plants within newly forming fairy circles are damaged only at the roots → strongly supports, since termites attack roots.
(B) Grass around circles surviving droughts → irrelevant.
 (C) Higher water content → weakens, since water is good for grass.
 (D) Clustering of circles → pattern, not cause.
 (E) Predators of termites nearby → irrelevant.
 Answer: A

Rickooreoisb · Answer

In your assessment of - (A) Dying grass plants within newly forming fairy circles are damaged only at the roots → strongly supports, since termites attack roots.

Where in the option is it mentiond that termintes are attacking roots, it could well be something else.

Vaishbab · Answer

Yeah I disagree with A being the right answer here. Even though it may be obvious, a connection between the 'burrowing' mentioned in the stem and the damaged roots sounds contrived since we don't know if the termites' burrowing actually affects plant roots.

E felt more relevant.

E felt more relevant.

GMATNinja · Answer

The scientists' hypothesis is that the   burrowing   activities of the sand termites that cause the circles to form. This implies damage done at or below the surface.

To understand why (A) supports the hypothesis, consider this counter-example: what if dying grass plants within newly forming fairy circles were damaged only   above   the surface (that is, on the blades of grass themselves)? That would be evidence (but not  proof ) that the damage is caused by something other than burrowing, since burrowing occurs at or below the surface. In that case, scientists might explore other possible explanations, such as a flying insect that feeds on the grass.

Instead, (A) is evidence (again, not proof) that the damage is in fact caused by burrowing, so (A) does support the hypothesis.

To be fair, the link between (A) and the conclusion isn't immediately obvious, so this one is pretty tricky.

In grasslands near the Namib Desert there are fairy circleslarge

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In grasslands near the Namib Desert there are fairy circleslarge

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