This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Psychiatry
Which of the following statement regarding dual sex therapy is true? 
Select and explain. 
A. Patient alone is not treated, B. Uses sildenafil, C. It treats sexual perversions, D. It is used for people with dual gender identities
A: Patient alone is not treated
Answer: A: Patient alone is not treated 
Explanation: The theoretical basis of dual-sex therapy is the concept of the marital unit or dyad as the object of therapy. In dual-sex therapy, treatment is based on a concept that the couple must be treated when a dysfunctional person is in a relationship. Because both are involved in a sexually distressing situation, both must paicipate in the therapy program. Dual sex therapy aka "Master and Johnson therapy".