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Difficulty: MediumWeaken

Environmental Engineer: To mitigate the urban heat island effect, city planners propose resurfacing municipal roads with a newly developed reflective polymer sealant. In trials on an open, isolated test track, asphalt coated with the sealant absorbed 60 percent less solar energy and maintained surface temperatures 8 degrees Celsius lower than untreated asphalt. Therefore, applying this sealant across the city's roadways will substantially reduce daytime ambient air temperatures in adjacent residential neighborhoods.

Which of the following, if true, most seriously weakens the environmental engineer's argument?

  1. A
    The reflective polymer sealant is substantially more expensive to produce and apply than the conventional sealants currently used on municipal roads.
  2. B
    The specialized thermal sensors used during the test track trials failed to measure the temperature of the asphalt at regular hourly intervals.
  3. In dense residential neighborhoods, solar radiation reflected by street surfaces is primarily absorbed by the vertical walls of adjacent buildings rather than escaping into the upper atmosphere.Answer
  4. D
    The reflective sealant also inhibits asphalt from retaining heat overnight, significantly lowering evening ambient temperatures in nearby parks.
  5. E
    Unless every single roadway in the metropolitan region is coated with the sealant, no neighborhood will experience any measurable reduction in daytime heat.

Answer

In dense residential neighborhoods, solar radiation reflected by street surfaces is primarily absorbed by the vertical walls of adjacent buildings rather than escaping into the upper atmosphere.
The conclusion relies on the assumption that lower surface temperatures on pavement will translate directly into cooler ambient air in residential areas. If reflected solar energy is captured and absorbed by the surrounding buildings, the thermal energy remains trapped within the neighborhood environment, preventing the predicted drop in ambient air temperature.

Step-by-Step Solution

1
Analyze the argument's structure and identify premises and conclusion.
Premise: Reflective sealant reduced surface heat by 8°C on an open test track. Conclusion: Applying the sealant across municipal roads will reduce ambient air temperatures in adjacent residential neighborhoods.
Weaken questions require identifying the inferential gap between experimental evidence and real-world application.
2
Identify the unstated assumption linking the premises to the conclusion.
The argument assumes that reducing pavement absorption on an open track will result in net atmospheric cooling in dense residential settings without redirecting thermal energy into surrounding structures.
Highlighting discrepancies between test conditions and actual urban environments exposes the logical vulnerability.
3
Evaluate choices for an alternative mechanism or factor that breaks this connection.
Showing that reflected solar radiation is absorbed by nearby building walls demonstrates that the heat remains in the neighborhood air layer, neutralizing the expected cooling effect.
Introducing a factor that undermines the causal outcome directly weakens the conclusion.

Key Concept

Evaluating causal arguments by identifying unrepresented differences between test environments and applied settings
Estimated Time:1m 15s
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