I believe the correct answer is the last option. Behaviorists believe that psychologists should focus on observable behaviors. It is an approach in psychology that focuses on behavioral aspects of the thought. For behaviorists, all of the behaviors are obtained by conditioning, wither by classical conditioning or operant conditioning. It happens by interaction with the environment. They believe that the responses made by people to the stimuli from the environment shape our overall actions and actions. Also, learning for them is just acquiring new behavior from the environmental conditions. Its general approach is based on the principle “stimulus-response” where in every stimulus there is always a corresponding response.