What was the main difference between the psychological thinking of Wilhelm Wundt and earlier philosophers who were also interested in thinking and behavior?

a. Wundt was European, earlier philosophers were American.

b. Wundt was the first professor from a major university interested in psychology.

c. Wundt was the first scholar to call himself a psychologist.

d. Wundt used psychotherapy techniques established by Freud to examine the thinking and behavior of healthy individuals.

e. Wundt and his students gathered data about human thinking and behavior in a laboratory setting.