Many urban planners advocate for increasing the density of residential areas as a primary strategy to reduce per capita carbon emissions. They cite studies showing that residents in denser urban environments tend to use public transportation more frequently, walk or cycle more, and live in smaller, more energy-efficient dwellings compared to their suburban counterparts. However, this strategy is unlikely to be effective in significantly mitigating overall carbon emissions.
Correct: B
The argument concludes that increasing residential density is 'unlikely to be effective in significantly mitigating overall carbon emissions.' To weaken this conclusion, we need to provide a reason why it *would* be effective, or that its effectiveness is underestimated. Choices A, C, and D all provide reasons why increasing density might *not* be effective in overall mitigation (e.g., construction emissions, infrastructure emissions, or limited scope), thus strengthening the conclusion. Choice B, however, weakens the conclusion. It posits that population growth is inevitable in metropolitan areas. If this growth is accommodated by dense housing, it leads to *substantially lower overall emissions* compared to the alternative of urban sprawl. This implies that increasing density *is* an effective strategy for mitigating overall carbon emissions, particularly when considering the inevitable growth and the less carbon-efficient alternative, directly undermining the claim that it is 'unlikely to be effective.'