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

Consider an Aggregate with the Fetch property set to Only On Demand. When does that Aggregate run?
A . Automatically, when the Aggregates set to run "At Start" finish.
B. Programmatically, using a Server Action.
C. Programmatically, using a Refresh Data node in a Screen Action.
D. Automatically, when the Screen is initializing.

Answer: C