Conservationists have begun removing plant species believed to be

Question

Conservationists have begun removing plant species believed to be nonnative, or introduced through human contact, from the Galápagos Islands to restore the islands’ ecosystem. But some of these species may be native after all. Humans first reached the Galápagos in 1535, but fossilized pollen grains of several species thought to be nonnative were found in sediment cores over 8,000 years old. Among these species is swamp hibiscus. This plant is spreading, which was taken as evidence of its invasiveness, but scientists now hypothesize that it is reclaiming habitat that was lost over time.

Which of the following would it be most useful to establish in order to evaluate the scientists’ hypothesis that swamp hibiscus is reclaiming habitat?

A. Whether swamp hibiscus provides food for any animal species native to the Galápagos

B. Whether swamp hibiscus found elsewhere is directly related to that growing in the Galápagos

C. Whether swamp hibiscus is native to areas from which the first humans to reach the Galápagos originated

D. Whether any nonnative plants recently removed from the Galápagos competed against swamp hibiscus for resources

E. Whether fossilized plant leaves have also been found on the Galápagos

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Official Answer

D

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KarishmaB · Accepted Answer

Premises: Conservationists have begun removing plant species believed to be nonnative from the Galápagos Islands to restore the islands’ ecosystem. But some of these species may be native after all (What does "these species" refer to here? The species "believed to be nonnative". So it is saying that some species that they thought were non native may actually be native) Humans first reached the Galápagos in 1535, but fossilized pollen grains of several species thought to be nonnative were found in sediment cores over 8,000 years old. Among these species is swamp hibiscus. (So pollen grains of swamp hibiscus have been found in sediments that are over 8000 years old) This plant is spreading (this is why they thought it is non native previously but not now) Hypothesis: Swamp hibiscus is reclaiming habitat that was lost over time. (which means that now they think that hibiscus is native and non native species had taken over its resources and now hibiscus is spreading as the non native species are being removed. So it is reclaiming its lost land) Which option will help us establish that swamp hibiscus was actually native and now it is reclaiming its lost land i.e. what will help strengthen the hypothesis? A. Whether swamp hibiscus provides food for any animal species native to the Galápagos Every native plant species needn't be food for some native animal species. B. Whether swamp hibiscus found elsewhere is directly related to that growing in the Galápagos No connection to whether it is native to Galapagos. C. Whether swamp hibiscus is native to areas from which the first humans to reach the Galápagos originated Irrelevant. It is possible that it was native there also and here also. D. Whether any nonnative plants recently removed from the Galápagos competed against swamp hibiscus for resources Correct. We know that non native plants are being removed and swamp hibiscus is spreading. So scientists think that it is reclaiming its own land. Yes - If we find that there was a non native species that was competing against swamp hibiscus for resources and it has been recently removed, that could show that swamp hibiscus is indeed reclaiming its lost land. This non native species would have taken over its land and now that it is being removed, hibiscus is coming back. No - If we find that there are no nonnative plants recently removed from the Galápagos that competed against swamp hibiscus for resources, then it doesn't explain why swamp hibiscus is spreading. Then it doesn't look like it is reclaiming its lost land. Doesn't look like another species had taken over its land in the first place. E . Whether fossilized plant leaves have also been found on the Galápagos Irrelevant. We know that pollen has been found. Whether leaves have been found or not is irrelevant. Answer (D) GMAT-Club-Forum-15o4mwwt.png

AnuK2222 · Answer

hi  Bunuel ,
can you explain on what basis option A is being rejected? 
thanks

visiblelights25 · Answer

Hi  AnuK2222 ,
The argument is about whether the plant is an invasive species (non-native) or a native of Galápagos Islands it doesn't say anything about providing food for any animal species, answering this question doesn't strengthen or weaken our argument either way so eliminate A

Kaushal124 · Answer

Hi Bunuel,

It would be a great help if you can share original explanation also.

ameya.satyawadi · Answer

This is evaluation based question for which It might strengthen or weaken the conclusion 'but scientists now hypothesize that it is reclaiming habitat that was lost over time'. Looking at the corresponding options a)Whether swamp hibiscus provides food for any animal species native to the Galápagos- irrelevant to the conclusion as it does not matter that the plant contributes in the ecological cycle for it to thrive as it may/may not be some organism's source of food but it may still be growing. out of scope. b) Whether swamp hibiscus found elsewhere is directly related to that growing in the Galápagos- what happens to swamp hibiscus elsewhere and how closely it is related here has nothing to do with its repopulation. c)Whether swamp hibiscus is native to areas from which the first humans to reach the Galápagos originated-The conclusion talks about swamp hisbiscus reclaiming the land so it has got nothing to do with its native status. d)Whether any nonnative plants recently removed from the Galápagos competed against swamp hibiscus for resources -Correct. When the swamp hisbiscus will be reclaiming land from another plant, it must be competing for resources with that species plus the nonative species that was recently removed must have given swamp hisbiscus the resources of land, soil etc which was necessary for the plantt to reclaim its land e)Whether fossilized plant leaves have also been found on the Galápagos-irrelevant as the conclusion is about the reclamation of territories which has got nothing to do with foosilized plant GMAT-Club-Forum-b5hrfqov.png

SergejK · Answer

As we read the question, we immediately see that the  focus is not on an existing conclusion  but on the  scientists' hypothesis . What could those scientists assume to counter the position that the swamp hibiscus is spreading and this is taken as a sign of its invasiveness with the hypothesis that it is reclaiming the habitat that was once lost? To reclaim something, one must lose it in the first place. So the habitat could be lost to actually those plants that were imported through humans. So an  assumption  could be that there were  nonnative plants that were removed so that the swamp hibiscus can now thrive . To evaluate the hypothesis we need an answer choice along the line of the assumption. D is the correct answer.

TtTt1212 · Answer

I am not so sure about option D. How can we be certain that these swarm hibiscus plants were not non-native? What if they are were also non-native and competed with the ones that were recently removed, as mentioned in D? 
 KarishmaB   MartyMurray   GMATNinja   Bunuel  - please let me know your thoughts!

Suyash1331 · Answer

how can D be the answer? even if some non native competed against hibiscus for resources that does not mean that hibiscus is reclaiming its habitat. it can also mean that there are two invasive species competing against each other GMAT-Club-Forum-5v5se2gq.png

GmatKnightTutor · Answer

Conservationists have begun removing plant species believed to be nonnative, or introduced through human contact, from the Galápagos Islands to restore the islands’ ecosystem. But some of these species may be native after all. Humans first reached the Galápagos in 1535, but fossilized pollen grains of several species thought to be nonnative were found in sediment cores over 8,000 years old. Among these species is swamp hibiscus. This plant is spreading, which was taken as evidence of its invasiveness, but scientists now hypothesize that it is reclaiming habitat that was lost over time.

Which of the following would it be most useful to establish in order to evaluate the scientists’ hypothesis that swamp hibiscus is reclaiming habitat?

Which of the following would it be most useful to establish in order to evaluate the scientists’ hypothesis that swamp hibiscus is reclaiming habitat?

Hello, people. Let’s get into this! We’re basically told about certain islands from which non-native plants are being removed. And how a specific plant is now beginning to spread. That there is a chance some of these non-native plans may have actually been native since there are pollen grains of some of these species in sediment cores thousands of years before humans got to these islands. And that the spreading of this specific plant which is one of them is actually the plant regaining terrain it once had in the past.

D. Whether any nonnative plants recently removed from the Galápagos competed against swamp hibiscus for resources

This is the answer. If it helps, imagine if the response to this statement was YES, SOME DID. It would support the scientists' hypothesis pretty well and serve as a strong reason for why the plant hibiscus is regaining territory currently. If, for example, there were some actual non-native plant species that used to compete with hibiscus for water and sunlight, it makes sense why hibiscus would start to spread once they were removed.

ChiranjeevSingh · Answer

Passage:

Sentence-by-Sentence Explanation

“Conservationists have begun removing plant species believed to be nonnative, or introduced through human contact, from the Galápagos Islands to restore the islands’ ecosystem.” 
 
  Meaning:  Conservationists are environmentalists or ecologists trying to protect the Galápagos Islands. They are removing plant species that they  believe  originated outside the islands (and likely arrived with the help of humans). The goal is to  restore  the islands’ original ecological balance.  
 
  “But some of these species may be native after all.” 
 
  Meaning:  This sentence introduces a contrast. It suggests that scientists might have  incorrectly  labeled some species as nonnative. Evidence has arisen indicating that they might  actually  be part of the original Galápagos flora.  
 
  “Humans first reached the Galápagos in 1535, but fossilized pollen grains of several species thought to be nonnative were found in sediment cores over 8,000 years old.” 
 
  Meaning:  This provides the evidence challenging the original assumption of “nonnative” status. If humans only arrived in 1535, but fossilized pollen from certain species (previously deemed introduced) dates back thousands of years  before  human contact, it suggests these species have long been present—so they are  native , not introduced.  
 
  “Among these species is swamp hibiscus.” 
 
  Meaning:  Now the passage highlights a specific plant—swamp hibiscus—as one example of a species once labeled “nonnative,” but which fossil evidence places on the islands thousands of years ago.  
 
  “This plant is spreading, which was taken as evidence of its invasiveness, but scientists now hypothesize that it is reclaiming habitat that was lost over time.” 
 
  Meaning: 
 
  First part (“This plant is spreading, which was taken as evidence of its invasiveness”):  Observers saw swamp hibiscus  expanding  in range and assumed that it must be an invasive newcomer—since rapid spread is often a hallmark of invasive species. 
  Second part (“but scientists now hypothesize that it is reclaiming habitat that was lost over time.”):  New research (particularly the fossil pollen) suggests swamp hibiscus might have been a  historic  resident. Its  current  expansion might be it “returning” to areas from which it was previously displaced, perhaps due to past ecological changes, human activity, or competition from genuinely introduced species.

Core Idea of the Passage

Overall, the passage presents a scenario where well-intentioned conservation efforts risk removing  truly native  species. The crucial piece of evidence is ancient fossil pollen that indicates some plants labeled “introduced” had actually been on the islands long before any human colonization. This forces conservationists to reconsider which plants are  truly  introduced/invasive and which are  native  and simply  re-expanding .

Option Analysis

A. Whether swamp hibiscus provides food for any animal species native to the Galápagos
 
  Not useful: 
 Whether or not local animals eat swamp hibiscus tells us nothing about whether the plant used to occupy and is now  reoccupying  a certain habitat. This option is about the ecological interactions in the present, but not the historical range of the plant or whether it was previously restricted by competition.

B. Whether swamp hibiscus found elsewhere is directly related to that growing in the Galápagos
 
  Not useful: 
 Even if scientists confirm that the Galápagos swamp hibiscus is genetically related to those in another region, that does not clarify if the Galápagos population is reclaiming territory it once occupied versus newly arriving. Pollen evidence already suggests swamp hibiscus has been there for thousands of years, so broader genetic relationships will not make us believe that swamp hibiscus came from other regions.

C. Whether swamp hibiscus is native to areas from which the first humans to reach the Galápagos originated
 
  Not useful: 
 The fact that pollen of swamp hibiscus dates to over 8,000 years ago on the islands already shows that  it predated human arrival  (1535 CE). Therefore, establishing its presence in humans’ home regions does not clarify whether the plant is currently spreading because it is “returning” to lost ground or because it was introduced  again  by humans.

D. Whether any nonnative plants recently removed from the Galápagos competed against swamp hibiscus for resources. 
 
  Useful 
The scientists’ hypothesis is that swamp hibiscus is “reclaiming” territory it once occupied rather than newly invading. To evaluate this claim, one key piece of evidence would be whether introduced (nonnative) species were previously outcompeting swamp hibiscus—i.e., preventing it from flourishing in areas where it once grew. If the removal of those nonnative plants coincides with swamp hibiscus spreading into areas documented (via fossils) to be part of its historical range, that would support the idea that it is reclaiming lost habitat rather than newly invading.

E. Whether fossilized plant leaves have also been found on the Galápagos
 
  Not useful: 
 Scientists already have evidence from fossilized pollen to prove the plant’s ancient presence. Discovering further evidence in the form of fossilized plant leaves would not shed new light on whether it is  now  reoccupying the same ground it once held, as opposed to occupying new territory.

(This solution was generated by ChatGPT o1. I have made minor edits (<10%) to the solution to make it more helpful.)

egmat · Answer

Here's how to approach this:

Step 1: Identify the Hypothesis to Evaluate

The scientists' hypothesis is that swamp hibiscus is "reclaiming habitat that was lost over time" rather than being invasive. This is a specific claim about why the plant is spreading across the Galápagos Islands.

Step 2: Spot the Evidence

What supports this idea? We know that:
 
 Fossilized pollen grains of swamp hibiscus were found in sediment cores over 8,000 years old 
 Humans first reached the Galápagos in 1535 
 The plant was present long before human arrival, suggesting it's native, not introduced

Step 3: Understand What "Evaluate" Means

For evaluate questions, we need information that would clearly support OR weaken the hypothesis depending on whether the answer is YES or NO. The best evaluation criterion creates a clear distinction between the two competing explanations: "reclaiming habitat" versus "invasive spreading."

Step 4: Find What Would Test This Hypothesis

Think about it: If swamp hibiscus is truly  reclaiming  habitat it once occupied, what would explain why it lost that habitat in the first place? And what would allow it to spread back now?

Choice D  gives us exactly this test: Whether any nonnative plants recently removed from the Galápagos competed against swamp hibiscus for resources.

Here's why this perfectly evaluates the hypothesis:

If YES (nonnative plants did compete):  This strongly supports the scientists' hypothesis. Removing competitor plants would naturally allow swamp hibiscus to expand back into areas where it was previously suppressed – perfectly explaining the spreading as "reclaiming habitat that was lost over time."
 
  If NO (no such competition existed):  This weakens the hypothesis. Without the removal of competitors, it's harder to explain the spreading as habitat reclamation rather than typical invasive behavior.

Why the other choices don't work:

Choice A:  Whether swamp hibiscus provides food for native animals tells us about ecological relationships but doesn't distinguish between reclaiming habitat versus invasive spreading.
 
  Choice B:  Whether swamp hibiscus found elsewhere is genetically related doesn't clarify the spreading pattern. The fossil evidence already established ancient presence.
 
  Choice C:  Whether swamp hibiscus is native to areas where first humans originated is irrelevant – we already know from fossils the plant was there 8,000+ years before humans arrived in 1535.
 
  Choice E:  Whether fossilized plant leaves have been found adds nothing new. We already have fossil pollen evidence of ancient presence, but this doesn't help evaluate the  current spreading pattern .

The key insight:  Notice how Choice D directly addresses the mechanism by which habitat could have been "lost" (competition from nonnative plants) and then "reclaimed" (those competitors being removed). This creates a testable scenario that distinguishes between the two explanations.

Answer: D

While this explanation covers the core reasoning, there's a lot more to mastering evaluate questions systematically. You can check out the  complete framework and detailed solution on Neuron by e-GMAT  to understand how to identify what truly evaluates a hypothesis in any CR argument and predict the evaluation criteria  before  looking at answer choices. You'll also find comprehensive explanations for  hundreds of other official GMAT questions on Neuron , complete with practice quizzes and detailed analytics to target your specific weaknesses.

Hope this helps! 🎯

iamjatinagrawal · Answer

The questions are easy but the problem is how well we are able to comprehend what the argument is saying and what kind of questions are we being asked in Evaluate the argument type questions.

How I got to the answer?

A. Whether swamp hibiscus provides food for any animal species native to the Galápagos  - Doesn't matter if it provides food or not but not helping in knowing whether its reclaiming its habitat.  ELIMINATE

B. Whether swamp hibiscus found elsewhere is directly related to that growing in the Galápagos  - Even if it is directly related, we don't know if the growth of this plant in  Galápagos  is responsible for the growth of this plant found elsewhere or vice versa. Incomplete information to consider this as a potential correct answer choice.  ELIMINATE

C. Whether swamp hibiscus is native to areas from which the first humans to reach the Galápagos originated  - If the plant is native to the place from which the first humans arrived, how does it matter, we are not getting to know about this plant if it is reclaiming its habitat in Galapagos.  ELIMINATE

E. Whether fossilized plant leaves have also been found on the Galápagos -  Are you getting any info on whether the plant is reclaiming its habitat if you get to know the answer to this question. No, right? Hence  ELIMINATE

And now we are left with this  Option (D)  which is the  correct answer.

Conservationists have begun removing plant species believed to be

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