Which theory did Skinner develop?

Which theory did Skinner develop?
 
  A) Operant conditioning theory
  B) Cognitive theory
  C) Rational emotive theory
  D) Human needs theory

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Which nursing theorist based her nursing theory, Interpersonal Relations in Nursing, on Sullivan's theory of Interpersonal Theory of Psychiatry?
 
  A) Watson
  B) Rodgers
  C) Peplau
  D) Roy

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Which theorist based his developmental theory on the premise that an individual does not and cannot exist apart from his or her relations with other people?
 
  A) Erickson
  B) Ellis
  C) Freud
  D) Sullivan

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Which developmental theorist continued his theory of human development throughout adulthood?
 
  A) Freud
  B) Erickson
  C) Sullivan
  D) Skinner