Logical ReasoningDifficulty: Medium

PT142 S2 Q15 Explanation

Often a type of organ

A free, expert breakdown of this official LSAT Logical Reasoning question.

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Stimulus

Often a type of organ or body structure is the only physically feasible means of accomplishing a given task, so it should be unsurprising if, like eyes or wings, that type of organ or body structure evolves at different times in a number of completely unrelated species. After all, animals have fundamentally similar needs and so _______ .

What this question is testing

Most Supported

Your task

Break the argument into its conclusion and evidence, then do exactly what the question stem asks with that structure.

Common trap

Answers that sound relevant to the topic but don't connect to the argument's actual reasoning.

Winning move

Predict what a right answer must do, then test each choice against the conclusion-evidence gap.

Reading along? Open the full official question in LawHub — we show a fragment here and keep the reasoning in our own words.

The question
15.

Which one of the following most logically completes the last sentence of

Answer choices

  1. Not About Cohabitation1% picked this

    will often live in the same environment as other species quite

    This blank is supposed to be about sharing similar organs / body parts, not about sharing a habitat.

  2. Correct74% picked this

    will in many instances evolve similar adaptations enabling them to satisfy

    Why this is right

    Yes, this loops back to connect with the first strand of the conversation, which is that very disparate animals end up with similar organs and body parts. Since there's only one way to accomplish task X, if lots of different animals need X, then evolution will favor mutations that allow the animal to accomplish X (and those adaptations will look very similar since there's only one way to get there)

    Skill tested: Most Supported · how this choice captures the argument's function is the move to repeat next time.

  3. Missing "Common" Part22% picked this

    will develop adaptations allowing them to satisfy

    This doesn't do as good a job of connecting back to the first sentence, since it doesn't emphasize that these adaptations will be strikingly similar to those of very different animals.

  4. Opposite: "different needs"2% picked this

    will resemble other species having different

    The thrust here is that "same needs" leads to "similar organs / body parts (resemblance)". This is talking about the similarity coming from different needs.

  5. Too Strong: "all"0% picked this

    will all develop eyes or wings

    Whenever LSAT authors name an example or two, in an offhand "such as X or Y" kind of way, those examples are not in any way crucial to the argument or the answer. It's more common than not that LSAT uses these examples to create a trap answer that is overvaluing the importance they played in the author's conversation. The author was never saying that animals will all develop eyes or wings. Those were just two examples of similar organs / body parts that are shared by many different types of animals.

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