Question 110·Medium·Inferences
Many municipalities have replaced their sodium-vapor streetlights with light-emitting diode (LED) fixtures, expecting to save money and reduce light pollution. In one midwestern city, researchers tracked energy use, skyglow, insect activity, and bird collisions before and after a pilot conversion from sodium lamps to dimmable, cool-white LEDs. Over two years, the city used 35 percent less electricity, but traps beneath the cool-white LEDs captured roughly three times as many insects as before, and springtime collisions of migrating birds with glass bus shelters rose by about 15 percent. Midway through the pilot, the city switched the same corridors to warmer LEDs and added full cut-off shields while keeping the dimming schedule; the increased skyglow and wildlife impacts then dropped close to pre-conversion levels, while energy savings persisted. Based on these findings, the research team suggests that future lighting upgrades in the city should _____
Which choice most logically completes the text?
For “Most logically completes the text” questions that follow a research summary, first restate in your own words the key findings—especially changes before and after any intervention. Then ask what a reasonable scientist or researcher would recommend that both reflects the evidence and balances the goals mentioned (here, energy savings and ecological impacts). Go through each option and quickly cross out any that ignore major results, contradict the data, or exaggerate uncertainty; the remaining choice should match the pattern of what worked best in the study.
Hints
Focus on the phrase before the blank
Look carefully at the sentence that leads into the blank: it asks what the research team suggests "based on these findings." Make sure you understand what "these findings" are.
Compare the two LED setups tested
What happened when the city first installed cool-white LEDs, and what changed after they switched to warmer LEDs with full shields? Think about energy use and effects on wildlife and skyglow.
Decide what a reasonable recommendation should balance
Should the researchers ignore ecological impacts to save energy, ignore energy savings to protect wildlife, or try to get both benefits at once? Eliminate any answer that clearly conflicts with the results described.
Check whether the study seems conclusive or not
Does the passage describe clear changes linked to each lighting setup, or does it say the results were unclear or mixed? Use that to judge answers that talk about reinstalling old lamps or delaying decisions.
Step-by-step Explanation
Identify the purpose of the blank
The blank comes after a description of a pilot project and its results. The phrase "Based on these findings, the research team suggests that future lighting upgrades in the city should" tells you that the correct answer must be a recommendation that follows logically from the specific evidence just described.
Summarize the key findings
The passage gives two main results:
- After switching from sodium lamps to cool-white LEDs, the city used 35% less electricity, but insect captures tripled and bird collisions increased about 15%. This shows energy savings but worse ecological impacts.
- Midway through, the city changed to warmer LEDs and added full cut-off shields, keeping the same dimming schedule. Skyglow and wildlife impacts dropped close to pre-conversion levels, and the energy savings continued. This shows that a different LED setup keeps the benefits while reducing harms.
Determine what a logical recommendation must do
A reasonable recommendation based on these results should:
- Keep the energy savings from LEDs (because 35% less electricity is a clear benefit), and
- Avoid or minimize the increased skyglow and wildlife impacts seen with the original cool-white, unshielded LEDs. So you are looking for a choice that preserves the second phase of the pilot (successful combination of savings + reduced harm), not the first phase or a return to the old system.
Test each answer choice against the findings
Now compare each option to the evidence:
- One option says to keep using the cool-white, unshielded LEDs. That directly goes against the evidence that these increased insect captures and bird collisions.
- Another option suggests reinstalling sodium-vapor lamps everywhere. That would get rid of the new problems but also throw away the 35% energy savings.
- Another says to delay upgrades because the results were inconclusive, but the passage clearly shows a strong before-and-after pattern for both types of LEDs.
- The remaining option recommends using warmer-spectrum, fully shielded LEDs in place of unshielded cool-white ones, which matches the second phase of the pilot that showed reduced ecological impacts and maintained energy savings.
Therefore, the correct answer is: C) adopt warmer-spectrum, fully shielded LEDs instead of unshielded cool-white fixtures, to reduce ecological impacts without sacrificing energy savings.