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Difficulty: EasyWeaken

A wildlife sanctuary reported a 40 percent decline in the local songbird population over the past two years, coinciding with the arrival of feral cats in the preserve. Because feral cats are known predators of small birds, sanctuary managers concluded that predation by the cats is the direct cause of this population decline.

Which of the following, if true, most seriously weakens the sanctuary managers' argument?

  1. A
    Dietary analyses of the sanctuary's feral cat population confirmed that songbirds constitute a substantial portion of their daily food intake.
  2. B
    Sanctuary managers failed to consult with local ornithological societies before permitting the feral cats to inhabit the reserve.
  3. A viral pathogen lethal to songbirds severely depleted avian populations across the entire geographical region over the past two years, including in preserves with no feral cats.Answer
  4. D
    The initial census that recorded songbird numbers prior to the cats' arrival was methodologically flawed and dramatically overestimated the baseline population.
  5. E
    Feral cats have never under any circumstances coexisted stably with indigenous songbird species in any ecosystem worldwide.

Answer

The statement introducing a widespread viral pathogen affecting songbird populations across areas with and without cats provides an alternate explanation, thereby weakening the causal conclusion.
The correct answer provides an alternate explanation for the songbird decline. Showing that songbird numbers fell just as sharply in adjacent preserves without feral cats strongly suggests that a regional factor, such as a pathogen, was responsible rather than predation by the cats.

Step-by-Step Solution

1
Identify the argument's premises and main conclusion.
Premise: Songbird population dropped by 40% over two years as feral cats arrived. Conclusion: Predation by feral cats directly caused the decline.
Weaken questions require targeting the logical bridge between stated premises and the conclusion.
2
Identify the underlying logical vulnerability.
The author presumes a correlation implies causation, overlooking potential external factors that could independently cause the decline.
Causal conclusions in logical reasoning are vulnerable to viable alternate causes.
3
Evaluate the answer choices for new information that severs the causal link.
Evidence of an overarching viral outbreak across the entire region demonstrates that the bird population declined even where feral cats were absent.
An alternate cause operating independently of the suspected factor directly undermines the proposed causal connection.

Key Concept

Causal Reasoning and Alternative Explanations
Estimated Time:1m 0s
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Topics

Weaken

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