What is the main function of a Filter activity in SFMC?

The main function of a Filter activity in Salesforce Marketing Cloud (SFMC) is to apply filter logic to create a subscriber group. This activity allows marketers to refine and segment their audiences based on specific criteria, such as demographics, behaviors, or engagement levels. By using filters, users can create targeted subscriber lists that enable more personalized and effective email marketing campaigns.

Creating subscriber segments through Filter activities helps in reaching the right audience with the right message at the right time, which can lead to improved engagement rates and overall campaign performance. The ability to define complex criteria for segmentation is crucial in maximizing the effectiveness of marketing efforts within SFMC. This is why option B accurately represents the primary function of a Filter activity.