A marketing company studied the effects of different forms of advertising (print; video) and types of product (candy; laundry) on attitudes toward the product. Liking scores were measured on a 5-point scales (1= dislike very much; 5 = like very much). The following mean liking scores were obtained: print-candy, 3; print-laundry, 2; video-candy, 4; video-laundry, 4). The test for the statistical interaction of the two independent variable would compare:

a. (3+2) and (4+4)

b. (3+4) and (2+4)

c. (3-2) and (4-4)

d. (3+2)/2 and (4+4)/2