Question

experimental group: seedlings grown with coffee grounds
control group: seedlings grown without coffee grounds
dependent variable: seedling height
answer bank: light, soil, temperature, seedlings given extra water

Explanation:

The independent variable is what is changed in an experiment. Here, the presence or absence of coffee - grounds is being changed. So the independent variable is the use of coffee grounds.

Answer:

seedlings given extra water is not relevant. The independent variable is the presence or absence of coffee grounds among the options in the context of this experiment. But from the answer - bank, there is no correct option as the answer - bank does not list "presence or absence of coffee grounds". However, if we assume we have to pick from the given options and consider that the experiment is likely trying to isolate the effect of coffee grounds while keeping other factors like light, soil, and temperature constant, then none of these are the independent variable being studied in relation to seedling height with/without coffee grounds. If we had to force a choice, none of the answer - bank options are correct for the independent variable of this experiment.