PrepTest 103

[lcid:3510] Prep Test 103 LSAT — Logical Reasoning — S3 Logical reasoning

Question prompt

A commercial insect trap 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

Weaken Questions

Stimulus Summary

Insect trap - Pesticide and glucose
Phenomenon - The trap becomes less effective over time
Explanation - The pests develop a resistance to the pesticide

Answer Anticipation

When a Weaken question falls into the Phenomenon/Explanation pattern (as almost all arguments that ask about hypotheses will), the correct answer almost always involves bringing up a viable alternative hypothesis/explanation. That’s particularly true when the stimulus itself suggests an alternative.
Here, the phenomenon is that insect traps become less effective over time. The explanation? Insects become resistant to the pesticide in the trap. However, we know that there are two ingredients in the traps - the pesticide, and the glucose. It’s equally possible that the reason the traps become less effective is that the insects become “resistant” in some way to the glucose.
Let’s find an answer that supports this alternative explanation - that the insects become less attracted to the glucose (since, say, all the bugs with a sweet tooth end up dying out).

Answer choices

  1. A
    In households where the Remaining source text redacted.
    Why choice A matches the stem
    This answer brings up the alternative possibility suggested by the stimulus and that we identified - the pests stop getting attracted to the glucose. Since this answer supports an alternative hypothesis, it weakens the argument for the hypothesis presented in the stimulus, so it’s the correct answer.

  2. B
    Even when only a Remaining source text redacted.
    Why choice B is not credited
    This answer supports the view that the insects would become resistant to the pesticide, supporting the hypothesis from the stimulus.

  3. C
    After eating glucose mixed Remaining source text redacted.
    Why choice C is not credited
    This answer aligns with the phenomenon in the stimulus, but it doesn’t provide any information that lines up or contradicts any potential explanation. It further strengthens the view that the insects are becoming resistant to the traps, but it doesn’t support a hypothesis as to why.

  4. D
    After the manufacturer of Remaining source text redacted.
    Why choice D is not credited
    There’s not enough information here to know what effect it has on the argument. It could strengthen it if the resistance is to the pesticide, no matter the concentration. It could weaken the argument if a resistance doesn’t fully protect against higher concentrations. Since we don’t know, we can’t say how this answer affects the argument, so we can rule it out.

  5. E
    The kind of glucose Remaining source text redacted.
    Why choice E is not credited
    This answer is completely out of scope. There being multiple kinds of glucose that appear naturally has nothing to do with whether it plays a role in the decreased effectiveness of the traps.

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