One Problem with the Dopamine Hypothesis of Schizophrenia Is

 One problem with the dopamine hypothesis of schizophrenia is

A) the lack of response to dopamine agonists shown by some patients.
B) the lack of response to dopamine antagonists shown by some patients.
C) research findings showing people with schizophrenia produce abnormal amounts of dopamine.
D) research findings showing people with schizophrenia have normal numbers of dopamine receptors.