Logical ReasoningDifficulty: Hard

PT134 S1 Q22 Explanation

Microbiologist: Because heavy metals

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

TopicsStrengthen

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Stimulus

Microbiologist: Because heavy metals are normally concentrated in sewage sludge during the sewage treatment process, the bacteria that survive in the sludge have evolved the unusual ability to resist heavy-metal poisoning. The same bacteria also show a strong resistance to antibiotics. This suggests that the sewage sludge has somehow promoted their resistance to antibiotics.

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
22.

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

Answer choices

  1. Too Weak9% picked this

    Most bacteria that are not resistant to antibiotics are not resistant to

    If a contrapositive of this statement were permitted, this would support the argument. But a most statement cannot be contraposed and so this statement is too weak. It leaves open the possibility that most bacteria that are resistant to heavy-metal poisoning are not resistant to antibiotics.

  2. Correct67% picked this

    Bacteria that live in sewage sludge that is free of heavy metals, but is in other respects similar to normal sewage, are generally resistant

    Why this is right

    This provides an example without the presumed cause [heavy metals] and without the effect [resistance to antibiotics].

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

  3. Weakens10% picked this

    Antibiotic resistance of bacteria that survive in sewage sludge in which heavy metals are concentrated contributes to their

    This suggests the causal relationship may be the reverse of the microbiologist’s argument.

  4. Weakens13% picked this

    Sewage sludge that contains high concentrations of heavy metals almost always contains significant

    This suggests that the resistance to antibiotics may be a result of exposure to antibiotics and not a result of exposure to heavy metals.

  5. Weakens1% picked this

    Many kinds of bacteria that do not live in sewage sludge are resistant to both

    This provides an example of the presumed effect [resistance to antibiotics] without the presumed cause [exposure to heavy metals].

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