Logical ReasoningDifficulty: Easy

PT139 S1 Q10 Explanation

Large deposits of the rare

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

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Stimulus

Large deposits of the rare mineral nahcolite formed in salty lakes 50 million to 52 million years ago during the Eocene epoch. Laboratory tests found that, in salty water, nahcolite can form only when parts per million of carbon dioxide.

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
10.

The statements above, if true, most strongly support which one of

Answer choices

  1. Trap1% picked this

    For most of the time since the Eocene epoch, the level of carbon dioxide in the atmosphere has been lower than it was

  2. Trap1% picked this

    Levels of carbon dioxide in the atmosphere fluctuated greatly during the

  3. Trap5% picked this

    Lakes were more likely to be salty during periods when the level of carbon dioxide in the atmosphere was at

  4. Correct93% picked this

    The atmosphere contained at least 1,125 parts per million of carbon dioxide during at least some part

    Why this is right

    Answer D is correct.

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

  5. Trap1% picked this

    No significant deposits of nahcolite have formed at any time since

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