Logical ReasoningDifficulty: Medium

PT115 S2 Q16 Explanation

Biologists agree that human beings

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

TopicsRole

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Stimulus

Biologists agree that human beings evolved from a fish, but they disagree about which species of fish. Since biologists agree that frogs are definitely related to the species of fish from which human beings evolved, on the basis of a close match between the mitochondrial DNA of lungfish and that of frogs (a saltwater fish) and that of tadpoles, claims that human beings must be descended from coelacanths.

What this question is testing

Role

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
16.

Which one of the following most accurately describes the role played in the dispute above by the proposition that frogs are definitely related to the species of fish

Answer choices

  1. Trap1% picked this

    Since it implies that human beings are not descended from lungfish, it is cited as evidence against the claim that

  2. Trap5% picked this

    Since it implies that human beings are not descended from coelacanths, it is offered as evidence against the claim that human

  3. Trap12% picked this

    It is offered as evidence for the contention that human beings must be descended from

  4. Correct73% picked this

    It is an assumption that both parties to the dispute use as a starting point for their

    Why this is right

    Answer D is correct.

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

  5. Trap8% picked this

    It implies that either a match of mitochondrial DNA or a match of hemoglobin between lungfish and coelacanths would show that human beings evolved

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