What does a dotted line from a "Group By" component to a "Filter" component mean?

To evaluate the "Group By" component, the "Filter" component is evaluated first.

There is a one-to-one relationship between the "Group By" and the "Filter" components.

Information from the "Group By" is copied over to the "Filter" component.

A property from the "Group By" is referenced by the "Filter" component.