When specifying a single running user of a dashboard, what does that user determine?

The correct choice highlights that the single running user of a dashboard influences which data is displayed based on their security settings. In Salesforce, the data visibility of a user is determined by their profile and role hierarchy. When a dashboard is run by this specified user, the dashboard respects the user's access levels to the underlying data, which means that only records that the user has permission to view will be displayed in the dashboard. This is crucial for maintaining data security and ensuring that users only see the information they are authorized to access.

While other options may present potentially valid points about dashboard functionality, they do not accurately reflect the primary role of the running user in determining data visibility. For instance, while the running user may be able to post snapshots to Chatter, that ability is not exclusive to them and does not significantly influence the essence of data display on the dashboard. Furthermore, there is no requirement for the running user to be the creator of the report, nor do they need the 'View All Data' permission to run a dashboard effectively. It’s essential for users to focus on how security settings dictate data visibility for enhanced understanding of Salesforce functionality.