Among the first-degree relatives of people with schizophrenia, endophenotypic abnormalities are ______.
a. no more prevalent than they are among those with no schizophrenic relatives
b. more prevalent than they are among those with no schizophrenic relatives
c. just as prevalent as they are among their relative(s) with schizophrenia
d. more prevalent than they are among their relative(s) with schizophrenia