<span>I believe it is light, but this is kind of a confusing question. Technically there is a independent and dependent variable in the question. The variable being manipulated is light, and the earthwork activity depends on the light. </span>
In a typical experiment two variables are used that are the independent and dependent variables. Dependent variable depends upon the change in the independent variable.
Here, light is the independent variable whose effect is to be observed on the dependent variable that is earthworm activity.
is defined as the group in an experiment or study that does not receive treatment by the researchers and is then used as a benchmark to measure how the other tested subjects do.
