Which of the following is a disadvantage of the experimental research method used in psychological studies?
O That two or more groups cannot be compared when we design an experiment.
O None of the above.
O That researchers cannot always manipulate variables they would like to study (or cannot randomly assign participants to certain
conditions), thus limiting the use of experiments to some, but not all variables.
O That we cannot be sure of the causal effects of one variable on another variable.