Your Text States That "For Many Years,psychologists Focused on Behavior

Your text states that "for many years,psychologists focused on behavior rather than mental states." Why did psychologists tend to neglect the mind during this period?

A) Mental states are unrelated to behavior.
B) Psychology does not include the study of the mind.
C) Mental states are inherently subjective.
D) The technology necessary to study the mind objectively has become available only recently.