Which is the predictor variable (X) and which is the criterion variable (Y) for each of the following examples?

(a) A researcher tests whether the size of an audience can predict the number of mistakes a student makes during a classroom presentation.

(b) A social psychologist tests whether the size of a toy in cereal boxes can predict preferences for that cereal.

(c) A military officer tests whether the duration of an overseas tour can predict the morale among troops overseas.