Logical reasoning PrepTest 103 · Section 3 · Question 18

Question prompt

A stingray without parasites 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

Facts

Valid or Flawed

NA

Question Type

Paradox Questions

Stimulus Summary

Stingrays are healthier without parasites, but stingrays without parasites evince an unhealthy environment.

Answer Anticipation

With Paradox questions, we generally want to clearly define the paradox ahead of anticipating an answer. Here, the opening line doesn’t present much of a paradox - it seems pretty straightforward that something without parasites is healthier than something with parasites!
So what’s the paradox? It derives from that second sentence. There, it says that stingrays without parasites indicate an unhealthy ecosystem. So while the stingrays might be feeling alright because they’re parasite-free, the ecosystem they’re living in is in trouble.
It’s really unclear what direction this question is going in, but let’s head to the answer choices and find something that connects a lack of parasites to an environment that is in distress.

Answer choices

  1. A
    During part of their Remaining source text redacted.
    Why choice A matches the stem
    This answer explains how a lack of parasites could be evidence for a sick environment. The parasites require shrimp and oysters, so if those organisms aren’t around, there would be no parasites. And Those organisms are environmentally vulnerable. So a sick environment would mean no shrimp/oysters, and thus no parasites, explaining how the parasite-free stingray could be evidence for a sick environment! This answer provides an explanation for the second sentence, so it’s the correct answer.

  2. B
    A stingray is a Remaining source text redacted.
    Why choice B is not credited
    This answer doesn’t tie into parasites at all - after all, parasites aren’t prey for the organisms they parasitize.

  3. C
    A parasite drains part Remaining source text redacted.
    Why choice C is not credited
    This doesn’t explain how a lack of parasites ties into environmental health.

  4. D
    An ecosystem can be Remaining source text redacted.
    Why choice D is not credited
    At the very least, we don’t know if stingrays are very simple organisms (and, in reality, we should say that they aren’t very simple organisms), so these environments with the stingrays wouldn’t trigger this conditional answer choice. This answer also doesn’t address parasites at all - and we also don’t know if the parasites are very simple!

  5. E
    Since the life of Remaining source text redacted.
    Why choice E is not credited
    This answer doesn’t tie into the environment at all, and that’s a key part of the paradox.

What this tests

Question analytics

Based on historical answer selection rates for this question.

Answer choice distribution

  1. A Credited 76%
  2. B 3%
  3. C 3%
  4. D 8%
  5. E 9%

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