In Discussing the Effectiveness of Behavioural Therapy, Cognitive Therapy, and Humanistic

In discussing the effectiveness of behavioural therapy, cognitive therapy, and humanistic therapy with a colleague, she suggests that the outcome is related to the dodo bird verdict. What does she mean?

A) None of the three will work for this disorder.
B) Behavioural therapy will be better because it focuses on extinction.
C) All three are likely to be equally effective.
D) Gender variables are unlikely to affect the outcome.
E) Humanistic therapy will be more effective because it is social by nature.