A study inference question tests what you can conclude when results change in different situations researchers studied. Read the sentence leading into the blank to see what link you need to explain. Then compare the situations and track what changes together, including everything the researchers measured. Observations can support a link without proving that one change caused another, so don't predict more than the results show. Wrong choices often give a cause the researchers never studied.
Hints
- Hint 1
Start with the sentence about higher rainfall. Identify both signs of reproductive success that Sung measured.
- Hint 2
In Sung’s final sentence, look for another change tied to rainfall. How can you connect it to the egg and tadpole results?
Step-by-step
Compare wetter and drier years
Step 1Identify the reproductive results
In higher-rainfall years, the frogs laid twice as many eggs, and the survival rate of tadpoles increased markedly. Since the blank asks what reproductive success is linked to, we need to use both the number of eggs laid and tadpole survival. What connects these results? Both measures improved in wetter years.
- Step 2
Connect the rainfall patterns
What else changes with rainfall? Sung says lower rainfall years coincide with a noticeable decline in the wetland’s insect population. The years when insects declined were the drier years, while the frogs reproduced more successfully in wetter years. But Sung observed these changes rather than testing their cause, so we can infer a link without proving why it happens.
- Step 3
Use the link Sung actually observed
Which choice links the frogs’ reproductive success to something Sung actually recorded? Genetic mutations, competition from other amphibian species, and predators migrating into the area all add things the passage never reports. The option about the availability of insects in the wetland uses the population change Sung observed without inventing another cause. Choice D.