The answer is B. a positive self-concept
Humanistic psychology deals with the individual as a unique person. It emphasizes the role of feelings and motives relating to self-esteem. And self-esteem can only be attained through a positive self-concept.
A and C are related. Reciprocal determinism is a theory proposed by Albert Bandura that says a person's behavior is very much influenced by personal factors and his environment. External locus of control is determined by the environment. For D, it's too far from the correct answer because empirical tests are only given to validate a person's personality.
