Question

why is it important for campaigns to know who uses different media? to reach their audiences effectively to combat effects of fake news to report accurate campaign data

Explanation:

Understanding media audiences allows campaigns to target the platforms their intended groups actually use, ensuring messages are seen by the right people instead of being wasted on irrelevant channels. The other options are not the core reason for this specific audience-media knowledge: combating fake news relates more to content verification, and accurate data reporting is a secondary outcome rather than the primary goal of knowing media users.

Answer:

to reach their audiences effectively