Answer: 4. Let's identify the most cost-effective method of advertising.
Explanation:
Marketing research encompasses all the processes involved in bettering the quality of goods and services as well as the distribution process.
Problem definition is the first stage which entails pointing out the what, when, why and how of a problem of interest. To arrive at a definition, the problem should be discussed with the decision-maker, secondary data analyzed, and qualitative research carried out.
The fourth option has arrived at a defined problem which is to ascertain the most cost-effective method of advertising.