Studies of Rates of Schizophrenia Among Adopted Children Have Shown

Studies of rates of schizophrenia among adopted children have shown that 

A) the presence of schizophrenia in the adopted parents correlated with schizophrenia in the adopted children. 
B) the presence of schizophrenia in the biological parents correlated with schizophrenia in the adopted children. 
C) the presence of schizophrenia in the adopted parents appeared to be as important as the presence of schizophrenia in the biological parents in predicting outcomes of the adopted children. 
D) neither schizophrenia in the adopted parents nor in the biological parents appeared related to the presence of schizophrenia in the adopted children.