All Successful Therapies,regardless of Approach,share What Key Element

All successful therapies,regardless of approach,share what key element?

A) They all use some form of transference to identify underlying problems.
B) They are able to replace a client's self-defeating,pessimistic life narrative with one that is more hopeful or attainable.
C) The therapists are scientific psychologists who rely on empirical research to determine the most effective technique for each client.
D) The therapists remain neutral and detached so that the clients can project their own issues into the therapy session.