A Main Effect in a Factorial Design Is

A main effect in a factorial design is

A) the most important outcome of the study.
B) an effect that has been hypothesized in advance, in contrast to an unanticipated effect that emerges from the study.
C) an outcome that occurs when two or more independent variables combine to produce an effect over and above their independent effects.
D) the effect that one independent variable has independently of the effect of the other independent variable.