Logical Reasoning

PT107 · S4 · Q1 Combustion of gasoline in automobile

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Combustion of gasoline in automobile engines produces benzene, a known carcinogen.

Author's Conclusion

The environmentalists' proposal — replacing gasoline with methanol — has little merit.

Author's Evidence

Gasoline combustion produces benzene (a carcinogen). Methanol combustion produces formaldehyde (also a carcinogen). So switching from one carcinogen to another doesn't help.

Evaluate

The author treats both carcinogens as equivalently bad. But carcinogens vary in potency. If formaldehyde is much less potent than benzene, then switching from gasoline to methanol meaningfully reduces cancer risk — making the environmentalists' proposal valuable.

Goal (per question stem: support the environmentalists' proposal)

Find an answer that establishes formaldehyde is less harmful than benzene — that flips the equivalence the author quietly assumed.

1.

Which one of the following, if true, most supports the environmentalists' proposal?

  1. The engines of some automobiles

    No Impact

    That some cars use diesel rather than gasoline is irrelevant to whether replacing gasoline with methanol would benefit public health. The argument compares gasoline and methanol; diesel cars sit outside that comparison entirely.

    1% picked this

  2. Several large research efforts are

    No Impact

    Research efforts to make cleaner gasoline are about a third option (improved gasoline), not about whether methanol is better than current gasoline. This neither supports the environmentalists' proposal nor the author's rebuttal.

    1% picked this

  3. In some regions, the local

    No Impact

    Local economic dependence on fuel industries might be a political consideration, but it doesn't address the public-health question the argument is about. The author claims the proposal lacks merit because of carcinogen production. Economic dependence doesn't speak to that claim either way.

    0% picked this

  4. Correct

    Formaldehyde is a less potent

    Why this is right

    This is the support the environmentalists need. The author treats the gasoline-to-methanol swap as a wash because both produce carcinogens — but that only holds if both carcinogens are equally bad. (D) tells us formaldehyde (the methanol byproduct) is less potent than benzene (the gasoline byproduct). So switching to methanol substitutes a less harmful carcinogen for a more harmful one — a meaningful health gain. The proposal does have merit.

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

    76% picked this

  5. Since methanol is water soluble,

    Opposite

    This actually weakens the environmentalists' proposal — methanol's greater water solubility means spills do more environmental damage. That's a reason to keep gasoline (or at least not switch to methanol), not to switch. We need an answer that supports the proposal, not one that gives an additional drawback.

    22% picked this

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