Why Is the Dissociative Coping Explanation of Dissociative Identity Disorder

Why is the dissociative coping explanation of dissociative identity disorder difficult to test?

A) Dissociative identity disorder is so rarely diagnosed that experimental subjects cannot be located.
B) Dissociative identity disorder is usually diagnosed in adulthood, and it is often impossible to verify whether the reports of childhood trauma are real or imagined.
C) People with dissociative identity disorder typically also suffer from extreme paranoia, so they are usually unwilling to participate in psychological research.
D) People with dissociative identity disorder rarely answer the same questions the same way twice, so it is impossible to draw conclusions from formal interviews or psychological tests.