When Looking for Abnormalities in the Brain as Clues to the Influences

When looking for abnormalities in the brain as clues to the influences of schizophrenia in correlational research,it is important to keep certain questions in mind.For example,if a person with schizophrenia were found to have an excess of dopamine,a researcher would need to ask all of the following questions :

A) Does too much dopamine cause schizophrenia?
B) Does having schizophrenia cause an excess of dopamine?
C) Is there some factor that causes both schizophrenia and an excess of dopamine?
D) Why is the dopamine system active in the schizophrenic brain?