Answer:
Control group: The fern in the closet.
Independent Variable: The 5 ferns.
Dependent Variable: The different colors of lights and the closet.
Constant: The 2 weeks the ferns were affected by the lights/closet.
Step-by-step explanation:
Control group is the one not given the special treatment in the experiment(in this case, the special treatment is the different lights).
Independent Variable is the thing(s) being affected in the experiment.
Dependent Variable is what's affecting the independent variable.
Constant is the quantity not being changed (in this case, the 2 weeks).