When does an Aggregate with the Fetch property set to Only On Demand run?

The Fetch property set to Only On Demand indicates that an Aggregate will not run automatically at any point during the screen's lifecycle. Instead, it is designed to be explicitly triggered when needed. This means the correct choice is that the Aggregate runs programmatically using a Refresh Data node in a Screen Action.

By using the Refresh Data node, you manually control when the data from the Aggregate is retrieved, offering greater flexibility in data loading and management. This is particularly useful in scenarios where you want to optimize performance by avoiding unnecessary data fetches until the user interacts with the interface that requires that specific information.

In contrast, the other options imply automatic execution or depend on the lifecycle of the screen or other Aggregates, which is not applicable for Aggregates set to fetch data only on demand.