In an Experiment Testing the Effectiveness of Five Different Advertisements

Multiple Choice

In an experiment testing the effectiveness of five different advertisements for a new product in five separate markets, sales of the new product are recorded at the end of each week for eight weeks. Analysis of variance is used to investigate whether the advertisements are equally successful.
-The total number of degrees of freedom for the design is

A) 35.
B) 4.
C) 7.
D) 28.
E) 39.