For experiment-based inference questions, identify the variable that was changed and summarize the result pattern (what changed and what did not). Then choose the option that restates that pattern with minimal added speculation, and eliminate choices that introduce untested causes, measurement critiques, or predictions beyond the study’s timeframe.
Hints
- Hint 1
Identify the one factor that changed
What condition differs among the three tank groups, and what conditions are explicitly described as identical?
- Hint 2
Track both outcomes
One measured trait changes with pH, and one does not change significantly. A good completion should reflect both facts.
- Hint 3
Be wary of untested explanations
Eliminate choices that rely on something the study didn’t measure or vary (for example, what would happen after eight weeks, or whether a different metric would show a change).
- Hint 4
Choose the closest supported inference
Prefer an option that summarizes the experimental pattern directly rather than adding speculative claims about measurement quality or future outcomes.
Step-by-step
- Step 1
Identify what changed and what was controlled
The snails were raised with the same timeframe and conditions like food and light, but the tanks differed in seawater pH (8.1, 7.8, 7.5).
- Step 2
Match the results to the correct kind of claim
Lower pH groups had thinner shells (12% and 27% declines), while soft-body mass did not differ significantly. So the best completion should connect lower pH to reduced shell thickness without claiming reduced body mass.
- Step 3
Select the choice that stays within the evidence
Choices that speculate about effects the study didn’t test (like what would happen over a longer time or whether mass is an imprecise measure) are weaker than a choice that directly reflects the reported pattern. The best-supported completion is: Lower ocean pH can lead juveniles to reach similar body mass but form thinner shells than at pH 8.1, potentially reducing their protection from predators.