Logical reasoning PrepTest 157 · Section 3 · Question 15

Question prompt

Ants sometimes live in Remaining source text redacted.
Why the credited answer is right

Credited answer: C

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

Argument or Facts

Argument

Valid or Flawed

Flawed

Strategy Overview

Argument or facts? Always argument, so identify premises and conclusions of argument Anticipate why the premises are not enough to show that the conclusion is true
Causal argument? Look for answer choice that:
Shows possible alternate cause Shows cause without effect Shows effect without cause Shows the cause and effect are reversed
If not causal argument, anticipate ways to worsen problem with argument
Use anticipations to select the answer choice that, if true, would weaken argument

Answer Anticipation

This question stem is a little confusing. We're asked to offer an "alternative explanation for the better health of orchids that house ants." Offering alternative explanations weakens an argument's explanation, so we can classify this as a Weaken question. Typically, we start Weaken questions by breaking down the argument and identifying its flaws. However, the question stem already did that for us. The question stem told us there might be an alternative explanation for the superior health of the orchids that house ants. We know the correct answer will provide an alternative explanation. We can try to anticipate a few alternative explanations for the orchids' better health. Maybe the ants protect against another organism that can harm the orchids' roots. Or maybe the ants help out the roots in some manner other than providing additional nutrients through organic matter. But we shouldn't get too attached to any specific anticipation. Instead, we'll approach the answer choices with an open mind. We'll ask, "Does this provide another explanation why orchids that house ants are healthier than orchids that do not?"

Answer choices

  1. A
    Microscopic organisms that are Remaining source text redacted.
    Why choice A is not credited

    This doesn't provide another explanation of why orchids that house ants are healthier than orchids that do not. If these microorganisms that break down the organic matter help the orchids' roots obtain nutrients from the matter, then this is entirely consistent with the passage's explanation. If the microorganisms do not help the roots get nutrients from the organic matter, then this may undermine the passage's explanation. However, this still wouldn't explain how the ants help the orchids be healthier. Therefore, this answer choice doesn't address the question proposed by the question stem.

  2. B
    The nutrients present in Remaining source text redacted.
    Why choice B is not credited

    This doesn't provide another explanation of why orchids that house ants are healthier than orchids that do not. Even if the organic matter's nutrients are already present in the soil, the ants could provide the orchids even more nutrients, helping the orchids become healthy. So, this answer choice is entirely consistent with the passage's explanation.

  3. C
    The ants that live Remaining source text redacted.
    Why choice C matches the stem

    Here we go. This answer choice provides a different explanation of why orchids that house ants are healthier than orchids that do not. According to this answer choice, the ants may not help the orchids by providing them nutrients. Instead, the ants help the orchids by fending off insects that eat the orchids' roots. Orchids that do not house ants would not have this protection, so it makes sense that the ant-less orchids would be less healthy. This answer choice provides an alternative explanation. We can justifiably select it and give the remaining options an, at most, cursory read.

  4. D
    The ants that live Remaining source text redacted.
    Why choice D is not credited

    This doesn't provide another explanation of why orchids that house ants are healthier than orchids that do not. If the ants did play a role in pollinating the flowers of the plant, that would be an alternative explanation for how the ants make the orchids healthier. But this answer choice says the ants do not play this role, so this answer choice does not address the question posed by the question stem.

  5. E
    Most plant species whose Remaining source text redacted.
    Why choice E is not credited

    This doesn't provide another explanation of why orchids that house ants are healthier than orchids that do not. Even if most plant species that harbor insects are more prone to disease and rot, some orchids could still benefit from ants. So, this doesn't necessarily weaken the argument. Even if did, it doesn't weaken the argument by providing an alternative explanation of why orchids that house ants are healthier. Therefore, this answer choice does not address the question posed by the question stem.

Question analytics

Based on historical answer selection rates for this question.

Answer choice distribution

  1. A 6%
  2. B 11%
  3. C Credited 81%
  4. D 2%
  5. E 0%

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