Psychology Made the Transition from Philosophy to Science with Which

Psychology made the transition from philosophy to science with which event?

A) William James changed the field's focus from structuralism to functionalism.
B) Plato died and interest in the philosophical aspects of psychology died with him.
C) G. Stanley Hall founded the American Psychological Association.
D) Titchener brought methods of introspection to the U.S.
E) Wundt opened his laboratory in Leipzig.