PrepTest 107

[lcid:3527] Prep Test 107 LSAT — Logical Reasoning — S4 Logical reasoning

Question prompt

Amphibian populations are declining Remaining source text redacted.
Why the credited answer is right

Credited answer: A

The notes below walk through why it fits the stem and how to eliminate the rest.

Argument or Facts

Argument

Valid or Flawed

Flawed

Question Type

Bizarro / Strengthen Questions

Stimulus Summary

The depletion of the ozone layer has correlated with a decline in amphibian populations
Ozone blocks UV-B UV-B damages genes Amphibians and their eggs lack features to protect them from UV-B
Therefore - The ozone layer being depleted is the primary cause of amphibians dying out

Answer Anticipation

Strengthen questions tend to have Correlation/Causation flaws, and Bizarro Strengthen questions are even more likely to feature that flaw. We should have headed into this stimulus looking to see if that flaw was present. The opening two lines bring up correlated phenomena (depletion of ozone layer; decline of amphibian populations), and the conclusion states that one of them is the primary cause of the other (the depletion of the ozone layer causing the decline of amphibian population).
When an argument features a Correlation/Causation flaw, there are a few common ways to strengthen it:
Eliminate an alternative cause Show more example of cause and effect going together Show a control group - no cause, no effect (e.g., amphibians that live in caves and aren’t exposed to the sun aren’t dying out) Explain how the causality works
Let’s head to the answers and eliminate any one that lines up with this.

Answer choices

  1. A
    Of the various types Remaining source text redacted.
    Why choice A matches the stem
    This is a tricky answer! It can feel as if it eliminates an alternative cause - other types of radiation. However, remember that the noted cause was the depletion of the ozone layer, not UV-B radiation, so this answer doesn’t eliminate alternatives. If anything, it limits the damage done to amphibians by the ozone depletion to the effects of UV-B. That either doesn’t affect the argument (since it changes nothing), or weakens it by eliminating more ways for the ozone layer depletion to lead to the noted effect, so this is the correct answer.
  2. B
    Amphibian populations are declining Remaining source text redacted.
    Why choice B is not credited
    This is an example of a control - for the species that are less affected by UV-B radiation from the ozone depletion, there’s less of a decline in population. That shows less cause, less effect, strengthening the argument for causality.
  3. C
    Atmospheric ozone has been Remaining source text redacted.
    Why choice C is not credited
    This answer establishes that the ozone depletion lines up directly with where the effect is seen, strengthening the argument that it’s the primary cause of it.
  4. D
    The natural habitat of Remaining source text redacted.
    Why choice D is not credited
    This answer eliminates an alternative cause. If their habitat had shrunk, then that may explain the decline in population instead of the ozone depletion. By eliminating that possibility, this answer strengthens the argument.
  5. E
    Amphibian populations have declined Remaining source text redacted.
    Why choice E is not credited
    This can seem out of scope if you didn’t note the timeline in the stimulus (we should have - timelines are always important!). However, the stimulus establishes the past 50 years as the timeline over which the ozone has continuously depleted. If that was matched by a continuous decline in amphibian population, that closely ties the two together, strengthening the argument that there’s a causal relationship between the two.

What this tests

Discussion

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