Answer:
Experiment
Explanation:
An experiment is simply said to be a planned inquiry or an investigation. psychologist are concerned with how to describe, explain, predict, and change behavior and the use of experiment helps them achieve their goal.. Usually, psychologists does experiments to know the probability of having a cause-and-effect relationship between different variables e.g when a researcher studies on if starving yourself of sleep affects the way you perform on a swimming test. experiment is the only research method mentioned here that allows the manipulation of an independent variable to test causation
