Answer:
The independent variable in the experiment is A. the jar covers.
Step-by-step explanation:
The independent variable in an experiment represents the thing that the person conducting the experiment changes or alters. One group in the experiment had covers (this represents the experimental group) and the other group had no cover (this represents the control group which was not exposed to the independent variable). Since the only thing that Redi changed between the two groups was whether or not the jars were covered, this represents the independent variable.
The number of jars and the contents of the jars were constant in both experiments, and the number of maggots on the meat is the dependent variable (the result of changing the independent variable).
Hope this helps!