Should an experiment test only one variable at a time? Why or why not?
A Yes, an experiment should test only one variable at a time. That way, the experiment will have to be performed only once.
B No, it is not necessary to test only one variable per experiment, especially when time is of the essence.
C As long as the experiment is repeated a sufficient number of times, it does not matter how many variables are used.
D Yes, an experiment should test only one variable at a time. This ensures that the experimental outcome is clearly due to one identifiable factor.