An inference question about a study tests what its observations support without saying it outright. Find the lines about each situation and sum up what happened. If the text reports a change over time, ask how the earlier observations connect to that change. Predict the smallest conclusion by going one step past the lines, while keeping track of when each result happened. Wrong choices often add reasons or effects that the study never tested.
Hints
- Hint 1
Look for the result in each kind of year. How did leg length relate to survival in dry years and in wet years?
- Hint 2
Connect reproduction in dry years to the final sentence. Who was more likely to reproduce, and how might that help explain the population’s change over time?
Step-by-step
Connect the yearly results to the population change
Step 1The dry-year advantage
In dry years, insects were scarce, and lizards with longer legs could travel farther in search of food. What do these observations support about those lizards? They were more likely to survive and reproduce, so longer legs helped them stay alive and leave offspring in those years.
- Step 2
The limit shown by wet years
Did longer legs help survival in wet years too? With insects plentiful, leg length did not affect survival rates, so the survival advantage belonged to dry years. That means the population could change over time even though longer legs didn’t help survival in every year.
- Step 3
The change across generations
How could those different chances of reproducing affect the population over twenty years? Longer-legged lizards could leave more offspring, so longer legs could become more common in later generations. That fits the final observation that the average leg length of the island lizard population had increased slightly. The choice with survival and reproduction advantage links the dry-year benefit to this small change. Choice B.