For a Specific Test to Function as a Vulnerability Marker

For a specific test to function as a vulnerability marker for schizophrenia, it is necessary that the proposed test

A) distinguishes between those who have schizophrenia and those who don't.
B) measures the level of dopamine and serotonin.
C) be designed to accommodate the communication difficulties typical of schizophrenia.
D) is used only with people who have no family history of schizophrenia.