Answer:
All options are correct.
Explanation:
The scientific experiments require proper procedure and experimental set up to perform the experiments. The results and observation was used for the interpretation of the experiment.
The experiments include both the dependent variable, independent variable control and set-up. Here, Shutle used the adult oyster and reef types as dependent and independent variable. Reefs are used as treatments and Oyster density changes and included in the category of density dependent variable.
Thus, all given options are correct.