LSAT Explanation PT 29, S4, Q1: Combustion of gasoline in automobile engines

LSAT Question Stem

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

Logical Reasoning Question Type

This is a Weaken question. 

Correct Answer

The correct answer to this question is D. 

LSAT Question Complete Explanation

In this passage, the argument revolves around the environmentalists' proposal to replace gasoline with methanol as a fuel source for automobiles. The structure of the argument is as follows:

Premise 1: Combustion of gasoline produces benzene, a known carcinogen.

Premise 2: Methanol does not produce significant quantities of benzene when burned.

Counterpremise: Combustion of methanol produces formaldehyde, also a known carcinogen.

Conclusion: The environmentalists' proposal has little merit.

The question type is a Weaken question, asking us to find the answer choice that most supports the environmentalists' proposal. In other words, we need to find an answer that weakens the conclusion that the proposal has little merit.

An "Evaluate" question for this argument could be: "Is formaldehyde less harmful than benzene?"

Now, let's analyze the answer choices:

a) The engines of some automobiles now on the road burn diesel fuel rather than gasoline.

- This answer choice doesn't address the comparison between gasoline and methanol, so it doesn't support the environmentalists' proposal.

b) Several large research efforts are under way to formulate cleaner-burning types of gasoline.

- While this might be true, it doesn't directly support the environmentalists' proposal to replace gasoline with methanol.

c) In some regions, the local economy is largely dependent on industries devoted to the production and distribution of automobile fuel.

- This answer choice is irrelevant to the argument as it doesn't address the merits of the environmentalists' proposal.

d) Formaldehyde is a less potent carcinogen than benzene.

- This is the correct answer. If formaldehyde is less potent than benzene, it supports the environmentalists' proposal by suggesting that methanol might be a better alternative to gasoline, despite producing formaldehyde.

e) Since methanol is water soluble, methanol spills are more damaging to the environment than gasoline spills.

- This answer choice actually weakens the environmentalists' proposal, as it suggests that methanol could be more harmful to the environment in case of spills.

In conclusion, the correct answer is D, as it provides support for the environmentalists' proposal by showing that the carcinogen produced by methanol combustion is less potent than the one produced by gasoline combustion.