Regarding Systematic Desensitization, Which of the Following Statements Is/are TRUE

Regarding systematic desensitization, which of the following statements is/are TRUE?

A) For most phobias, desensitization works best when people are directly exposed to the stimuli and situations they fear.
B) For a simple phobia, like spider phobia, the procedure can be successfully done in groups.
C) For some fears, like riding in an elevator, desensitization can be completed in one session.
D) All of these statements are true.