The Textbook Suggests That There Is a Great Irony Involved

The textbook suggests that there is a great irony involved in research on schizophrenia which is that

A) the original physicain who developed the diagnostic category was later diagnosed with schizophrenia himself.
B) for over 100 years we have known the diagnostic category that we now recognize as schizophrenia may well be composed of many different kinds of mental disorders.
C) we have had a clear model of the cause of schizophrenia for over 100 years, but still no effective treatment.
D) None of these are what the textbook suggests.