Which of the following steps is necessary to make a related action visible to users?

In order to make a related action visible to users, it is necessary to set it up correctly within the application’s user interface. One of the key components in this setup is the Views and Headers tab, where you can configure how related actions are displayed to users.

By navigating to the Views and Headers tab, you can manage which related actions are tied to a specific record or interface. This step ensures that the action is not only available for execution but is also visible and accessible within the app's layout. This setup is particularly crucial for user experience, as it allows users to find and use related actions effectively.

Other options, while relevant to different aspects of application setup, do not directly impact the visibility of a related action. For example, linking to a security group pertains to permissions rather than visibility, publishing the application is about making the entire application live, and setting default values relates to field behaviors in forms. Hence, focusing on the Views and Headers tab is the targeted approach to ensure the desired visibility of related actions for users.