Psychologist: There are theories that posit completely different causal mechanisms from those posited by Freudian psychological theory and that are more successful at predicting human behavior. Ttherefore, Freudian theories of behavior, no matter how suggestive or complex they are, ought to be abandoned in favor of these other theories. Which one of the following is an assumption on which the psychologist's argument depends? ['Freudian theories have offered interesting suggestions, which have been shown to be false, about the causes of human behavior.', 'Freudian theory has had little success in predicting how people will behave in various situations.', 'Measuring the predictive success of a psychological theory involves considering other theories that attempt to explain the same phenomena.', 'A psychological theory with greater predictive success than another is scientifically preferable to it.']