My take on this question, which was the toughest one for me in the entire Verbal portion of the Diagnostic Test:
GMAT™ Official Guide 2020, Diagnostic Test, Critical Reasoning, Page 32, Question 74.Key points: The question asks about what would undermine an argument. Again, the focus is on the
argument.
Breakdown:
1) The question could not be more straightforward:
weakens the argument.
2) The passage describes the feeding and nesting habits of guillemots, a type of Arctic bird. Notice the transition “therefore” ahead of the last sentence. Whatever follows must be a conclusion based on the evidence that was presented before. In this case, temperature rises are expected to increase the range of the guillemots to more northerly areas. The positive correlation of
increase in temperature, increase in range lies at the heart of the argument.
Answers:
(A)
killed by an unusually early snowAnalysis: This sort of device could be thought of as an anti-
deus ex machina, with the weather intervening to kill something rather than save it. Part of the correlation outlined above is addressed here, the increase in temperature, but the other part, about the range, is not. Moreover, “there will still be years” suggests that there will also not be years… and in the end, such a speculative construct does nothing to advance or devalue an argument. Red light.
(B)
predators are likely to extend
their own rangeAnalysis: This is as transparent a response as you could hope to find in a Critical Reasoning question. Both parts of the correlation are present: Arctic warming and a northward-extending range. “Their own” means that the guillemot range will also likely extend north. With both increases escaping attack, the argument would remain unscathed, which is
the opposite of what the question asks. Red light.
(C)
coastal areas, where temperatures are generally higherAnalysis: This statement says that guillemots nest in an established manner, seeking out warmer coastal areas. It is given in the passage that their range “was limited to the southernmost Arctic
coast” (my italics). Perhaps they would be content with the coast they already occupy if temperatures increased, which would have no effect on their range. But perhaps not. Some guillemots could indeed move farther north if those coasts warmed up. Due to the nuances of these questions, I want to see if I can disprove the remaining two answers to feel better about picking this one. Yellow light.
(D)
thin ice in the southern Arctic will disappearAnalysis: It is unclear what the fish would do if the thin sheets of ice disappeared, and it is therefore unpredictable what the birds that prey on them would do in turn. If we are inclined to believe that the fish and their guillemot predators need the thin ice, then if anything, an exodus from the southern Arctic would be expected, and that would not necessarily increase the range of the guillemots. Yellow light.
(E)
The fish… are currently preyed on by other predators
Analysis: Rising temperatures are missing altogether from this statement, and if the guillemots currently face more competition for the fish they desire, then they clearly must have risen to the occasion, since their range lies in the predator-dense southern coastal areas of the Arctic. This answer is more
off-topic than some of the others; it is difficult to make a prediction one way or the other about the range of the guillemots without more information. Red light.
This is another tough one for me, as no answer leaps out as being the one and only that can be justified. At its base, the argument deals with movement, an
expansion. Consulting the passage again, I see that the second line says that guillemots “feed on fish… and they nest on nearby land.” That illustrates a simple relationship--where they eat → where they nest. There is nothing about eating in choice (C), leaving the statement more open to interpretation. The guillemots might prefer the warmer northerly coasts, but they might not. That is, their range could stay the same, but it could also increase as some of the birds migrated to warmer coastal regions in the north while others stayed behind and enjoyed the relatively more comfortable southerly temperatures. But with (D), you can bet that if the fish moved, the birds and their eventual nests would move as well, and that sort of movement would not represent an expansion, but more of a relocation. Since that
would weaken the argument, I am going to go with (D).
Guessing: Phew, I dodged a bullet there. You will probably have noticed by now that I find open-ended questions, which require a degree of speculation to work, much more difficult than their closed-loop counterparts. Add to that the fact that three of the five answer choices here--(A), (B), and (D)--rely on a conditional if-then construct, and I have to focus extra hard on looking for flaws. Still, I want you to appreciate that (A), (B), and (E) are all easier to remove from the equation (for reasons discussed above), and that that leaves a 50/50 for further consideration.
Keep putting yourself in a 50/50 position, and you are going to walk away with more correct answers.Good luck with your studies.
- Andrew
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Please use
official questions from the Official Guide or Verbal Review to practice for the Verbal section.