Question 53·200 Super-Hard SAT Reading Questions·Information and Ideas
Marine biologists studied how nighttime coastal lighting affects the percentage of coral larvae that attach to a reef surface, a process called settlement. They exposed larvae from two coral species to amber or blue light at either low or high intensity; the high-intensity treatments used twice the light level of the low-intensity treatments. The researchers concluded that at a site currently exposed to high-intensity blue light, switching to high-intensity amber light would preserve settlement more effectively than keeping blue light and reducing its intensity by half.
Which choice most effectively uses data from the graph to support the researchers’ conclusion?
For a graph-based command-of-evidence question, translate each proposed action into a graph treatment and identify any common baseline. Compare the changes or final outcomes across the claim’s full scope, including every relevant group, and choose the evidence that supports the complete comparison rather than only one strategy or one group.
Hints
Identify the endpoints
Determine which graph treatment represents each of the two proposed changes from high-intensity blue light.
Use the common starting point
Because both strategies begin with the same treatment, calculate the change in settlement from that treatment to each proposed endpoint.
Check the complete scope
Look for evidence that compares the effectiveness of both strategies for both coral species.
Step-by-step Explanation
Identify the two strategies
Switching color while maintaining intensity leads from high-intensity blue to high-intensity amber. Halving the intensity while retaining the color leads from high-intensity blue to low-intensity blue.
Calculate the changes
For mustard hill coral, switching to high-intensity amber produces a gain of percentage points, while halving blue-light intensity produces a gain of points. For mountainous star coral, the corresponding gains are points and points.
Compare the strategies
For each species, the gain from switching to high-intensity amber is greater than the gain from reducing blue-light intensity. This directly supports the researchers’ comparative conclusion.