State the degrees of freedom error in each of the following tests.
(a) A researcher tests how nervous public speakers get in front of a small, medium, or large audience. Ten participants are randomly assigned to each group.
(b) A consultant measures job satisfaction in a sample of 15 supervisors, 15 managers, or 15 executives at a local firm.
(c) A high school counselor has 12 students in each of four classes rate how much they like their teacher.