Trout populations are rising in United States rivers, which suggests it is time to shift conservation efforts from keeping raw...
GMAT Critical Reasoning : (CR) Questions
Trout populations are rising in United States rivers, which suggests it is time to shift conservation efforts from keeping raw numbers high to having the right kind of trout in the right area. For years, nonnative trout species were used to stock rivers for fishing, and these new arrivals crowded out indigenous species. Conservation should thus focus on restoring habitats, since habitat restoration will enable indigenous trout populations to rebound, and since __________.
Which of the following, if true, would most logically complete the argument?
Passage Analysis:
| Text from Passage | Analysis |
| Trout populations are rising in United States rivers, which suggests it is time to shift conservation efforts from keeping raw numbers high to having the right kind of trout in the right area. |
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| For years, nonnative trout species were used to stock rivers for fishing, and these new arrivals crowded out indigenous species. |
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| Conservation should thus focus on restoring habitats, since habitat restoration will enable indigenous trout populations to rebound, and since _________. |
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Argument Flow:
The argument moves from current success (rising trout numbers) to identifying a new goal (right species in right places), then explains the historical problem (non-native species crowding out natives), and finally proposes a solution (habitat restoration) while leaving space for an additional supporting reason.
Main Conclusion:
Conservation efforts should focus on restoring habitats rather than just maintaining high trout numbers.
Logical Structure:
The conclusion is supported by the premise that habitat restoration helps native species rebound, but the argument structure shows we need a second supporting premise to complete the reasoning chain from 'why habitat restoration is the right approach.'
Prethinking:
Question type:
Logically Completes - We need to find a statement that provides a second reason supporting why conservation should focus on habitat restoration, completing the 'since...and since...' structure.
Precision of Claims
The argument deals with quality-focused conservation (right species in right places) vs quantity-focused conservation (keeping numbers high), and the activity of habitat restoration as the proposed solution.
Strategy
Look for a second supporting reason that logically backs up the conclusion that conservation should focus on habitat restoration. This reason should complement the first reason (habitat restoration helps indigenous populations rebound) and strengthen the overall case for shifting from quantity-focused to quality-focused conservation.
This choice states that habitat degradation caused the initial trout population declines. This works perfectly as the second supporting reason because it establishes habitat degradation as the root cause of the problem. If habitat degradation caused the original decline, then habitat restoration (fixing the root cause) becomes the logical solution. This creates a strong causal chain: habitat degradation led to declines → therefore habitat restoration will address the fundamental issue. This complements the first reason (habitat restoration helps indigenous populations rebound) and strengthens the overall argument for shifting conservation focus. This is our answer.
This choice discusses keeping nonnative trout populations under control through increased fishing levels. While this might be relevant to managing trout populations, it doesn't provide a second reason for why conservation should focus on habitat restoration specifically. Instead, it suggests a fishing-based solution rather than supporting the habitat restoration approach. This doesn't fit the logical structure we need.
This choice mentions that the right kind of trout are increasing in some areas with habitat degradation. This actually works against the argument rather than supporting it. If the right kind of trout can increase even in degraded habitats, this would weaken the case for focusing on habitat restoration. We need a reason that supports habitat restoration, not one that suggests it might not be necessary.
This choice simply restates that restoring habitats focuses conservation efforts, but this is essentially circular reasoning. We're trying to argue WHY conservation should focus on habitat restoration, so saying that habitat restoration focuses conservation efforts doesn't provide an additional supporting reason. This doesn't add any new logical support to the argument.
This choice claims that the overabundance of indigenous trout caused habitat degradation. This contradicts the overall flow of the argument, which suggests that nonnative species crowded out indigenous species (implying indigenous trout were not overabundant). Additionally, this would suggest that having more indigenous trout is problematic, which goes against the goal of helping indigenous populations rebound through habitat restoration.