Why Has There Been Little Systematic Research Conducted on Dissociative

Why has there been little systematic research conducted on dissociative amnesia and fugue?

A) These conditions are too rare to permit more extensive study.
B) The diagnosis of both disorders is too controversial; until a consensus is reached as to whether or not there is a true "psychogenic" amnesia, further study is virtually impossible.
C) Case studies provide more useful information.
D) Both disorders are relatively brief, preventing researchers from having ample time to systematically conduct full evaluations.