单选题 The parents of a male adolescent diagnosed with anorexia nervosa ask the nurse how long their son's treatment will take. The most therapeutic response by the nurse would be
A．"Treatment of anorexia nervosa takes a long time and setbacks are common. "
B．"Most anorectic adolescents respond favorably to treatment within a few weeks. "
C．"Your son's prognosis depends on your willingness to become involved in therapy. "
D．"Your son's progress depends on determining what triggered his desire to lose weight. /