Descartes' Theory About Emotion Was Replaced by the James-Lange Theory

Descartes' theory about emotion was replaced by the James-Lange theory and was then later replaced by the Cannon-Bard theory and then was changed to the theory of emotions as learned reflexes. This change about theories of emotions demonstrates

A) the establishment of rules.
B) assumptions held about a phenomenon.
C) organizing principles or ideas.
D) changes in scientific knowledge.