How can a system administrator resolve the issue of a non-visible New Button for a marketing user on the campaign home page?

Selecting the Marketing User checkbox in the user record is the correct solution because this action is essential for enabling marketing-specific features and functionalities in Salesforce, specifically for users who are designated as marketing personnel. When this checkbox is activated, it grants the user the necessary permissions to create and manage campaigns effectively, including the visibility of the New Button on the campaign home page.

The New Button is specifically tied to the user's role as a marketing user. Without this designation, the user may be limited in their campaign management capabilities, including not seeing the options relevant to their marketing responsibilities. Thus, ensuring that this checkbox is selected aligns the user's profile with the requirements to access the marketing features within Salesforce.

While other choices might relate to permissions or access, they do not directly target the specific issue of visibility for marketing users in terms of being recognized as part of the marketing function.