A Researcher Investigating the Link Between Stressful Life Events and Depression

A researcher investigating the link between stressful life events and depression has decided to use a prospective research design. This means that the researcher will have to

A) select subjects with the prospect of becoming depressed.
B) select subjects with the prospect of experiencing stress.
C) follow subjects over time to see if stress predicts the onset of depression.
D) question subjects carefully to see if their depression has always followed some identifiable stress.