Aresearcher in a retail-marketing unit wanted to test the impact of four different advertising campaigns for a new product on a group of forty randomly selected consumers. she wanted to compare the impact of each advertising campaign on each individual consumer's likelihood of purchasing the product and across the whole group, as well as any interaction effects. what sort of test design best suits this study?

(a) independent factorial design
(b) anova
(c) repeated-measures factorial design
(d) multiple linear regression.