In the Factorial Experiment, Where a Is the Number

Multiple Choice

In the factorial experiment, where a is the number of levels for factor A, b is the number of levels for factor B, and r is the number of replications of each of the ab factor combinations, the degrees of freedom for interaction is given by which of the listed expressions below?

A) (a - 1) (b - 1)
B) (a - 1) (r - 1)
C) (b - 1) (r - 1)
D) ab(r - 1)