Which of the following is NOT a way to report on a campaign in HubSpot?

Campaign reporting is indeed a fundamental feature available in HubSpot's marketing dashboard, which allows users to assess the performance and impact of their marketing campaigns comprehensively. This reporting functionality encompasses a variety of methods to analyze campaign metrics, including downloading metrics, accessing real-time analytics, and utilizing a custom report builder.

By stating "None of the above," it affirms that all the listed methods—downloading metrics, viewing analytics in real time, and employing the custom report builder—are valid ways to report on a campaign. Hence, this choice correctly highlights that it is not an option to say that these methods do not exist for campaign reporting in HubSpot. Each listed method contributes to a robust understanding of campaign performance, making the ability to report on campaigns a well-integrated feature within HubSpot's marketing tools.