Which Statement Is True Concerning the Treatment of Conversion Disorders

Which statement is true concerning the treatment of conversion disorders?

A) Controlled research has not been conducted even though the number of contemporary conversion disorder cases is adequate for such research.
B) Case studies of psychoanalytic treatment of conversion disorder have shown success.
C) Outcome research disputes the success of the psychoanalytic treatment of conversion disorders.
D) Freud's and Breuer's treatment of conversion disorders might have been successful, but the treatment of more modern psychoanalysts has not been successful.