Logical ReasoningDifficulty: Easy

PT128 S3 Q2 Explanation

Because metallic mirrors absorb some

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

TopicsMain Conclusion

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Stimulus

Because metallic mirrors absorb some light, they waste energy. When light strikes a metallic mirror, electrons in the mirror move, using energy and dimming the reflected image. As a result, metallic mirrors cannot be used loss is important, such as high-powered lasers.

What this question is testing

Main Conclusion

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
2.

Which one of the following most accurately expresses the argument's

Answer choices

  1. Inference Bait3% picked this

    Metallic mirrors reduce the effectiveness of

    This is an inference that we could draw, not the conclusion the argument did draw.

  2. Premise1% picked this

    Part of the light falling on metallic mirrors tends to be

    This is a paraphrase of the first half of the first sentence, which is a premise.

  3. Inference Bait1% picked this

    High-powered lasers require mirrors that conserve

    This claim is well supported (though not entirely supported) but the argument, but it's not the argument's explicitly stated conclusion. That makes it Inference Bait. It's well supported because high-powered lasers were given as an example of the type of application for which conserving energy is important. It isn't 100% supported, though, because we don't actually know whether high-powered lasers require the use of mirrors at all.

  4. Out of Scope: most significant disadvantage4% picked this

    A tendency to waste energy is the most significant disadvantage of

    This isn't explicitly stated in the argument so it can't be the correct answer. The argument isn't concerned with naming the most significant disadvantage of metallic mirrors.

  5. Correct91% picked this

    Metallic mirrors are unsuitable for applications where it is crucial to

    Why this is right

    This is a good paraphrase for "metallic mirrors cannot be used in applications in which minimizing energy loss is important."

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

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