Question 11·Medium·Inferences
While reviewing satellite images, hydrologist Maya Chen noticed that a river's floodplain has become dotted with new ponds over the past decade. Local reports attribute the ponds to heavier rainfall, but Chen isn't convinced. She points out that the ponds cluster along stretches where beavers have recently recolonized after a decades-long absence, and that nearby areas without beavers saw no similar change despite comparable rainfall.
Based on Chen's observations, which inference is best supported?
For SAT inference questions, focus strictly on what the passage shows, not what could be true in general. Identify the contrast or pattern the author or researcher points out (here, beaver vs. non-beaver areas with similar rainfall), then choose the option that restates the most reasonable conclusion from that evidence without adding new claims or making the conclusion broader than the data supports. Eliminate answers that contradict the passage, introduce new facts, or overgeneralize the result.
Hints
Focus on the scientist’s doubt
Why is Chen not convinced by the local reports that heavier rainfall explains the ponds? Look at the evidence she uses to question that explanation.
Compare beaver areas to non-beaver areas
What important difference does Chen point out between stretches with beavers and stretches without beavers, given that rainfall was comparable?
Check for overgeneralizations or new claims
Eliminate choices that introduce ideas not mentioned in the passage (like changes in overall regional rainfall or beaver behavior that wasn’t described), or that make claims much broader than the evidence supports.
Step-by-step Explanation
Identify what locals think is causing the ponds
First, note the explanation given by local reports: they say the new ponds are due to heavier rainfall. This is the current hypothesis that Chen is questioning.
Examine Chen’s key observations
Chen notices two important things:
- The new ponds cluster along stretches where beavers have recently recolonized.
- Nearby areas without beavers had no similar change, even though they had comparable rainfall.
This means rainfall levels were roughly the same in both beaver and non-beaver areas, but only the beaver areas got new ponds.
Draw the logical inference from the contrast
Because rainfall was comparable in both areas, but new ponds appeared only where beavers returned, rainfall by itself cannot explain the ponds. The key difference is beaver presence, so it is reasonable to infer that beaver activity is a likely driver of the new ponds, not rainfall alone.