In their evaluation of Titchener's theoretical viewpoint toward the end of his career, Schultz and Schultz conclude that he was ____.?

a. ?too rigid and dogmatic to ever change
b. ?a minor figure in the history of modern psychology
c. ?too tied to Wundtian thought to make any original contributions of his own
d. ?as flexible and open to change as scientists are supposed to be
e. ?None of the choices are correct

d