Answer: Pavlov, Watson and Skinner
Explanation: Pavlov is a famous Behavioral psychologist who tried to show through his experiment that Dogs can give a conditioned response to particular set of stimuli such as the sounding of Bell.
Watson is a Behavioral psychologist who believes that only Behaviors that can be observed, recorded and measured are of value in the study of human Behavior.
Skinner also known as the Father of Operant conditioning states that Individual's response to stimuli in an environment is the main determinant of Behavior.