Logical reasoning PrepTest 113 · Section 3 · Question 8

Question prompt

For all species of Remaining source text redacted.
Why the credited answer is right

Credited answer: B

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

Cannot Be True Questions

Stimulus Summary

Higher animals: Reproduction → Eggs
Some species are all female (including some salamanders)
Eggs without fertilization - DNA nearly the same as a single parent, making the species less adaptive than two-parent species

Answer Anticipation

Cannot be True questions task us with finding an answer that is directly contradicted by the information in the stimulus. And, in general, it’s much easier to contradict a strong statement than a weak statement - and it’s especially easy to contradict a conditional statement.
Here, the opening statement (at least, the first half of it) is conditional:
Reproduction → Eggs
To contradict a conditional statement, an answer would need to establish the sufficient condition is present without the necessary condition - a species that reproduces but doesn’t produce eggs.
The rest of the statements are weaker (“not necessarily”, “some”, “nearly identical” which is moderately but not absolutely strong), and thus are much less likely to lead to correct answers here.
However, there is one more statement that we should strongly anticipate might lead to a correct answer - the comparative one. Single-parent species with nearly identical genetic codes between parents and children are “less adaptive” than two-parent species. While we need to be careful about answers that aren’t comparative (we can’t pick an answer stating that a species is or isn’t adaptive), answers that compare species that fall into the two camps on their adaptiveness could be contradicted by this comparison.

Answer choices

  1. A
    There are some species Remaining source text redacted.
    Why choice A is not credited
    The stimulus discusses only a “rare” female-only salamander species, so it’s absolutely possible that other salamander species have both genders.
  2. B
    There are some species Remaining source text redacted.
    Why choice B matches the stem
    Reproduction requires eggs, so any species is going to need to produce eggs. After all, if it can’t reproduce, it’s not going to exist! This answer violates the opening conditional, so it cannot be true. (Note that the definition of species involves being able to reproduce. You wouldn’t be expected to know this, but you would have been expected to pick this answer because a species that can’t reproduce would cease to exist, as there would be no new members of that species.)
  3. C
    There is a significant Remaining source text redacted.
    Why choice C is not credited
    This answer can be tempting because we’re told that the female-only salamander species is “rare.” However, two issues here. First, that qualifier applies only to that species - maybe that species is rare (it’s found only in one cave in South America), but species that are female-only are actually quite common. Second, how many is “significant”? The word has a specific meaning on the LSAT - enough to be relevant/matter. It’s a bit of a wishy-washy word because of that, and since we don’t have any information about what would be significant or how many of these species exist, we can’t say this answer is contradicted.
  4. D
    Some species of higher Remaining source text redacted.
    Why choice D is not credited
    We know that these species will be more adaptive than species with single parents, but that doesn’t mean that they’ll be particularly adaptive. “More adaptive” than something that’s exceptionally unadaptive can still be quite unadaptive itself!
  5. E
    Some offspring of species Remaining source text redacted.
    Why choice E is not credited
    The stimulus does note that the “nearly identical” genetic codes of offspring in female-only species makes that species less adaptive than species with male and female members, so we can infer that the latter species don’t have genetic codes nearly identical to a single parent. However, that doesn’t mean that the genetic codes are equally similar to both parents - there still could be a skew towards one parent. Since we can’t tell if this answer lines up with the stimulus or not, it could be true and is thus wrong.

What this tests

Question analytics

Based on historical answer selection rates for this question.

Answer choice distribution

  1. A 5%
  2. B Credited 79%
  3. C 7%
  4. D 6%
  5. E 3%

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