A Researcher Predicts That Tennis Professionals Will Play Better in Front

A researcher predicts that tennis professionals will play better in front of an audience. Less capable tennis players, however, are expected to do better without an audience. The researcher

A) is predicting a main effect for the audience variable.
B) is predicting a main effect for ability of the tennis player.
C) expects an interaction effect to occur.
D) is using a mixed design.