<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.
To maintain homeostasis, unicellular organisms grow, respond to the environment, transform energy, and reproduce. A single-celled, or unicellular, organism does everything you would expect a living thing to do.
