Answer:
a. Independent Variable: different sized aquariums
b. Dependent Variable: number of surviving fish
c. Controlled Variables/Constants: amount and type of food, aquarium maintenance and water temperature
d. Experimental Controls/Control Groups: none
Step-by-step explanation:
In an experiment, the dependent variable is the condition that is being measured or tested in the experimental procedure, while the independent variable isn't changed and serves to measure the outcome of the dependent variable. Moreover, the constant variables are those conditions that stay the same in the experiment. As observed in the case above described, an experiment usually has multiple constant variables. Finally, a control group is composed of individuals/research subjects who do not receive the experimental treatment, and therefore they can be used to compare the outcomes observed in the experimental groups.