What Does the Textbook Indicate Is the Reason Why Classic

What does the textbook indicate is the reason why classic approaches, such as transactional analysis and Jungian analysis, have been replaced in textbooks by others, such as cognitive-behavioral therapy?

A) Perls was too confronting and cantankerous for therapists to buy into his approaches.
B) Perls himself was not successful in helping his clients using the classical approaches.
C) The concepts in approaches such as transactional analysis were too complicated for widespread adoption.
D) Perls himself abandoned his original approaches for contemporary ones that promoted faster change in clients.
E) The contemporary cognitive-behavioral therapies claim to be empirically supported and/or "proven" effective with certain populations and clusters of symptoms.