GMAT Focus EditionVerbal ReasoningEasy
A recent study revealed that cities with extensive public transportation networks experience significantly lower rates of traffic-related air pollution compared to cities that rely primarily on private automobiles. This finding suggests that investing in public transportation could be an effective strategy for improving urban air quality. Which of the following, if true, most strengthens the argument?
- AThe study controlled for population density and industrial activity, which are known contributors to air pollution.
- BPublic transportation systems often require significant public funding and can be costly to maintain.
- CSome residents in cities with extensive public transportation still prefer to use their private cars for daily commutes.
- DMany cities with extensive public transportation also have strict emissions standards for private vehicles.
Show answer & explanationAnswer & explanation
Correct answer: A. The study controlled for population density and industrial activity, which are known contributors to air pollution.
The argument links public transportation to improved air quality. Strengthening the argument requires demonstrating that this link is direct and not due to other factors. Option B directly addresses potential alternative causes for lower pollution, making the connection more robust.
Why the other options are wrong
- B. This discusses the cost of public transportation, which is irrelevant to its effectiveness in reducing air pollution.
- C. This points to a limitation in public transportation usage, but doesn't directly weaken or strengthen the link between public transport and air quality for those who do use it.
- D. This suggests an alternative cause for lower pollution, potentially weakening or at least not strengthening the argument that public transport is the primary factor.
Strengthening an Argument
To strengthen an argument means to provide additional evidence or reasoning that makes the conclusion more likely to be true, often by ruling out alternative explanations or confirming a causal link.
- Eliminates alternative causes.
- Provides additional supporting evidence.
- Confirms the stated causal relationship.
Memory trick: Strong arguments eliminate rivals and confirm connections.