WeakenDiff: Easy
Logic Breakdown
Passage Summary: Critics say big triple-trailer trucks are dangerous, but the data shows they have fewer fatal accidents per mile in the West than the national average for regular trucks, so they must be safer.
Conclusion: Triple-trailer trucks are actually safer than other types of commercial vehicles.
Reasoning: In Western regions where they are allowed, triple-trailers have a lower fatality rate per mile than the national average for other commercial trucks.
Analysis: The author is making an unfair 'apples-to-oranges' comparison by pitting a specific geographic region against a national average. The Western highways where these trucks are permitted might be significantly safer—flatter, straighter, or less congested—than the variety of roads included in the national average. To weaken this, we should look for an answer that suggests the low accident rate is a result of the driving environment rather than the safety of the trucks themselves. If regular trucks are also safer in those specific Western areas, the author's conclusion loses its legs.
Conclusion: Triple-trailer trucks are actually safer than other types of commercial vehicles.
Reasoning: In Western regions where they are allowed, triple-trailers have a lower fatality rate per mile than the national average for other commercial trucks.
Analysis: The author is making an unfair 'apples-to-oranges' comparison by pitting a specific geographic region against a national average. The Western highways where these trucks are permitted might be significantly safer—flatter, straighter, or less congested—than the variety of roads included in the national average. To weaken this, we should look for an answer that suggests the low accident rate is a result of the driving environment rather than the safety of the trucks themselves. If regular trucks are also safer in those specific Western areas, the author's conclusion loses its legs.
Passage Stimulus
Passage Redacted
Unlock Full Passage3.Which one of the following, if true, most substantially weakens the argument?
Correct Answer
B
B highlights a crucial confound: western highways are less traveled and thus safer than the national system overall. That means the lower fatality rate could be due to safer conditions in the West, not because triple-trailers are inherently safer vehicles. This directly undermines the argument’s key comparison.
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