Answer:
Focus group
Step-by-step explanation:
A focus group refers to a form of marketing research whereby 6 to 10 individuals are called forth in a room or virtual digital rooms, wherein they are asked to provide feedback w.r.t a product or a service or on a marketing campaign.
A trained individual presides over the session, carrying a list of about 10 to 15 questions and seeking response from all the participants present in the room.
The participants represent buyers who are selected based upon their buying history, behavioral and other basis of marketing segmentation. Usually, to obtain diverse ideas and feedback, such focus groups are held at different cities.
In the given case, Marty brought together a group of soft drink consumers so as to avail their feedback with respect to the marketing slogans, the firm has been considering. Thus, to serve the purpose, it is recommended that the firm conduct a focus group.