Which organizational pattern is used in the passage comparing desalination and water recycling for cities?
As freshwater supplies tighten, cities increasingly evaluate alternative water sources that can withstand drought. Desalination removes salt from seawater, creating a new supply that is not dependent on rainfall. Water recycling, similarly, treats wastewater to a high standard so it can be reused for irrigation, industry, or even drinking after advanced purification. In contrast, the two approaches differ in energy demand and in where they can be deployed.
Desalination plants often require substantial electricity to push water through membranes, and they produce a concentrated brine that must be disposed of carefully to protect marine ecosystems. Recycling systems can also use significant energy, yet they are typically located within existing water networks and can reduce pollution entering rivers. Consequently, some cities find recycling more immediately scalable, especially when they already operate modern treatment facilities.
However, the passage cautions against assuming a universal best choice. Coastal cities with limited groundwater may consider desalination as a reliable backup, while inland cities may rely more heavily on recycling because transporting seawater is impractical. As a result, planners often compare costs, energy sources, and environmental impacts before selecting a portfolio of options. The author concludes that understanding similarities and contrasts helps decision-makers choose resilient strategies rather than relying on a single, oversimplified solution.
- It uses compare and contrast, signaled by “similarly” and “in contrast,” to evaluate two options. (correct answer)
- It uses chronological sequence, tracing each technology’s invention year by year without comparisons.
- It uses cause and effect only, attributing all water shortages to a single immediate cause.
- It uses definition only, explaining key terms without discussing trade-offs or decisions.
Explanation: This question tests upper-level reading comprehension skills: identifying organizational patterns in texts. The passage comparing desalination and water recycling uses a clear compare and contrast organizational pattern. The text systematically compares these two water supply alternatives across multiple dimensions: their basic processes, energy demands, implementation locations, and suitability for different cities. Key transitional phrases like "similarly" and "in contrast" explicitly signal this comparative structure throughout the passage. Choice A is correct because it accurately identifies the compare/contrast pattern and notes the specific signal words used. Choice B incorrectly suggests chronological sequence when the passage analyzes current technologies; C wrongly claims pure cause-and-effect; and D incorrectly states definition only when the passage clearly discusses trade-offs and decisions. The comparative structure helps readers understand the advantages and limitations of each technology to make informed decisions about water resource management.