Until when must ZAE protect holding pattern airspace?

The requirement for protecting holding pattern airspace in the context provided stops "until approach advises the arrival is tower jurisdiction." This is crucial because, as long as the aircraft remains in the holding pattern under the jurisdiction of the approach control, it is the responsibility of the approach controller to ensure safe separation and traffic management.

Once the approach controller informs that the aircraft has transitioned to tower jurisdiction, the responsibility shifts to the tower controller. At this point, the tower controller can safely integrate the arriving aircraft into the landing sequence, allowing for adjustments in airspace protection based on the current traffic and operational needs.

Recognizing the transition from approach to tower jurisdiction is essential for ensuring smooth operations and safety during landing phases, thus making this the correct answer to the question posed.