ZAE is responsible for separating departing aircraft from what?

The role of ZAE, or a non-radar approach control facility, is to ensure safe separation of departing aircraft, which is crucial for maintaining safe operations in the airspace system. The correct choice highlights that ZAE is responsible for separating departing aircraft from arriving aircraft that are still within the same airspace. This is an essential function because arriving aircraft may be on approach to land, and their flight path can overlap with that of departing aircraft. Proper separation ensures that conflicts between the two types of traffic do not arise, thereby preventing potential accidents and promoting safety.

The other options, while relevant in different contexts, do not fully encapsulate the complete responsibility of ZAE regarding departures. Focusing solely on separating departing aircraft from other departures or only considering aircraft that are about to take off does not account for the critical interactions that happen with arriving traffic already in the airspace.