Why is it difficult to determine whether or not individuals with gender identity disorder have a heterosexual or a homosexual orientation?

A) because defense mechanisms are very strong and do not allow the unconscious tendencies to surface

B) because most report having bisexual tendencies so they really don't express a preference

C) because the definition of their orientation could be based on either their assigned sex or their gender identity

D) because their gender identity confusion also makes them feel confused about their sexual orientation as well