Statistical interaction refers to which of the following?

(a) Association exists between two variables.

(b) The effect of an explanatory variable on a response variable changes greatly over the levels of a control variable.

(c) The partial association is the same at each level of the control variable, but it is different from the overall bivariate association, ignoring the control variable.

(d) For a collection of three variables, each pair of variables is associated.

(e) All of the above.