Techniques Such as Meta-Analysis Are Useful in Psychology Because

Techniques such as meta-analysis are useful in psychology because:

A) they allow for the careful study of behaviour in schools, workplaces, and other natural contexts.
B) rarely does one study prove anything, and this technique analyzes data from many studies.
C) they include subjects who are exposed to experimental conditions that do not include the independent variable.
D) they help reduce unintended changes in subjects' behaviour due to cues given by the experimenter.