Logical ReasoningDifficulty: Easy

PT143 S4 Q4 Explanation

In polluted industrial English

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

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Stimulus

In polluted industrial English cities during the Industrial Revolution, two plant diseases—black spot, which infects roses, and tar spot, which infects sycamore trees—disappeared. It pollution eradicated these diseases.

What this question is testing

Strengthen

Your task

Find the choice that makes the argument's conclusion more likely to be true.

Common trap

Answers that are consistent with the argument but add no real support, or that strengthen a claim the argument doesn't make.

Winning move

Locate the gap between evidence and conclusion, then pick the choice that closes it.

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

The question
4.

Which one of the following, if true, most strengthens the

Answer choices

  1. Weakens1% picked this

    Scientists theorize that some plants can develop a resistance to

    This makes it a little less likely that air pollution eradicated black spot and tar spot.

  2. Weakens1% picked this

    Certain measures help prevent infection by black spot and tar spot, but once infection occurs, it is

    That black spot and tar spot are difficult to eradicate makes it less likely that air pollution eradicated these diseases.

  3. Too Weak0% picked this

    For many plant species, scientists have not determined the effects of

    This answer does not specify which plant species.

  4. Correct94% picked this

    Black spot and tar spot returned when the air in the cities

    Why this is right

    This is an example where the cause is absent and the effect is absent.

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

  5. Weakens4% picked this

    Black spot and tar spot were the only plant diseases that disappeared in any English cities

    If air pollution is what caused the disappearance of black spot and tar spot, why didn’t it also eradicate other plant diseases?

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