Don Martin owns DME Ads Inc., an advertising agency. At present, the company focuses solely on advertising. However, Don plans to expand the company's focus to include all the major elements of an organization's promotional mix. Don feels that expanding the focus in such a way will allow the firm to meet customer needs in a more coordinated fashion. Currently, the firm organizes its work according to the media being used. Don believes this is the most effective way to subdivide advertising. Because television is one of the most widely used advertising media, the company spends most of its time on television advertising DME knows what it takes to get the job done, and it is committed to success. Refer to DME Ads Inc. As Don plans to expand the company's focus to other major elements of the promotion mix, which of the following should he focus on if he wants to help his clients create and maintain favorable relationships with their various internal and external groups? a. Word-of-mouth b. Personal selling c. Public relations d. Advertising e. Sales promotion