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Difficulty: HardLogical Arguments and Causal Relationships

An urban ecology study across 40 metropolitan districts evaluated the impact of municipal sanitation infrastructure on local avian populations over a five-year period. In districts that replaced traditional open trash receptacles with sealed, animal-proof containment bins, researchers recorded a 40% reduction in local crow populations within 18 months. The researchers hypothesized that restricting access to human food waste directly caused the decline in the local crow population.

Consider the following two logical roles regarding the researchers' causal hypothesis:
- Column 1: A statement that, if true, most strongly SUPPORTS the hypothesis.
- Column 2: A statement that, if true, most strongly WEAKENS the hypothesis by demonstrating a causal direction reversal or an unaddressed alternative cause.

Which of the following joint selections correctly identifies a supporting statement for Column 1 and a weakening statement for Column 2?

  1. Column 1: Adjacent control districts maintaining open receptacles showed stable crow populations, while tagged crows in sealed-bin districts exhibited severe caloric deficits; Column 2: Municipalities installed sealed bins specifically in response to a pre-existing drop in crow numbers caused by an avian pox outbreak.Answer
  2. B
    Column 1: Municipalities installed sealed bins specifically in response to a pre-existing drop in crow numbers caused by an avian pox outbreak; Column 2: Adjacent control districts maintaining open receptacles showed stable crow populations, while tagged crows in sealed-bin districts exhibited severe caloric deficits.
  3. C
    Column 1: Crows in sealed-bin districts shifted their primary foraging grounds to neighboring open-receptacle districts, causing local counts in sealed-bin districts to drop; Column 2: Open trash receptacles attract a wide variety of urban scavengers in addition to crows.
  4. D
    Column 1: Adjacent control districts maintaining open receptacles showed stable crow populations, while tagged crows in sealed-bin districts exhibited severe caloric deficits; Column 2: Sealed bins also reduced the local population of urban rodents that rely on spilled organic waste.
  5. E
    Column 1: The overall mass of organic waste collected in sealed-bin districts increased during the study period; Column 2: Crows are highly intelligent birds capable of learning new foraging behaviors.

Answer

Column 1: Adjacent control districts maintaining open receptacles showed stable crow populations, while tagged crows in sealed-bin districts exhibited severe caloric deficits; Column 2: Municipalities installed sealed bins specifically in response to a pre-existing drop in crow numbers caused by an avian pox outbreak.
The correct selection properly aligns both logical roles. For Column 1, evidence that control districts with open bins maintained stable populations while crows in sealed-bin districts suffered caloric deficits directly supports the claim that food waste restriction caused the population decline. For Column 2, evidence that bin installation occurred in response to a pre-existing decline caused by avian pox undermines the hypothesis by reversing the temporal sequence (showing the population drop came first) and introducing an alternative cause.

Step-by-Step Solution

1
Analyze the causal claim in the stem.
Cause: Restricting access to human food waste via sealed bins. Effect: 40% reduction in local crow population.
To evaluate support and weaken statements, the precise independent cause and dependent effect must be clearly isolated.
2
Identify the criteria for Column 1 (Support).
Column 1 requires evidence showing that the absence of the cause (control districts with open bins) prevents the effect, and that the proposed mechanism (caloric restriction) is active in the treatment group.
Demonstrating control stability alongside evidence of the hypothesized mechanism strongly reinforces a causal link.
3
Identify the criteria for Column 2 (Weaken via Causal Reversal / Alternative Cause).
Column 2 requires a statement showing either that the decline in crow population occurred prior to bin installation (causal direction reversal) or was driven by an unmeasured confounder (avian pox outbreak).
If the decline in crows caused the installation of bins rather than vice versa, the researchers' causal hypothesis is completely invalidated.
4
Evaluate the joint options to find the correct pairing.
The option placing the control group / caloric deficit evidence in Column 1 and the pre-existing disease / reversed timeline evidence in Column 2 is the unique correct pairing.
Only this option places both logically complementary statements in their correct designated columns without reversal or irrelevance.

Key Concept

Two-Part Analysis Causal Argument Evaluation & Reversal Identification
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Topics

Logical Arguments and Causal Relationships

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