Research Studies of the Effectiveness of Hypnosis as a Form

Research studies of the effectiveness of hypnosis as a form of therapy have demonstrated that

A) for problems of addiction,such as smoking,hypnosis has not been especially effective.
B) posthypnotic suggestions have helped alleviate headaches,asthma,and stress-related skin disorders.
C) as a form of therapy,hypnosis is no more effective than positive suggestions given without hypnosis.
D) all of these statements are true.