Logical ReasoningDifficulty: Easy

PT122 S1 Q2 Explanation

A study of plaque buildup

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

TopicsParadox

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Stimulus

A study of plaque buildup on teeth used three randomly assigned groups of people who brushed their teeth twice a day for a year. People in Group 1 used the same toothbrush all year. People in Group 2 used the same toothbrush all year but sterilized it each month. People in Group plaque buildup as each other, while people in Group 3 had less plaque buildup.

What this question is testing

Paradox

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, if true, most helps to explain the relative amounts of plaque buildup found

Answer choices

  1. Trap7% picked this

    The buildup of plaque on teeth, which brushing twice a day helps to prevent, is accelerated by the growth of bacteria on toothbrushes that

  2. Correct91% picked this

    The stiffness of the bristles on new toothbrushes, which the mechanical action of brushing destroys after several months,

    Why this is right

    Answer B is correct.

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

  3. Trap0% picked this

    The people who did the study measured the amount of plaque buildup by a new method not

  4. Trap2% picked this

    Before they joined the study, some of the people in Group 3 had been in the habit of brushing their

  5. Trap0% picked this

    The people in Group 2 and Group 3 brushed their teeth as vigorously as did the

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