Schizophrenia Was Not Included in the World Health Organization Mental

Schizophrenia was not included in the World Health Organization Mental Health Survey Consortium (2004) because

A) previous research had shown that schizophrenia is strictly a North American phenomenon.
B) previous research had shown that many people diagnosed with schizophrenia would also receive a diagnosis included in the surveys.
C) schizophrenia was not of interest to the researchers.
D) all of the above.