What service must ZAE provide for GWO TWR?

The correct service ZAE must provide for GWO TWR is approach and departure control services. This is crucial because approach and departure control are vital for ensuring the safe and efficient management of aircraft as they enter and exit the terminal airspace around GWO airport. This includes guidance for aircraft during their landing and takeoff phases, providing instructions on altitude, heading, and speed, which helps to maintain safe separation between aircraft.

This type of control service is a significant responsibility of terminal air traffic control units, and it's essential for preventing collisions and ensuring smooth operational flow. The accurate sequencing and spacing of aircraft are paramount, particularly in busy air traffic environments.

The other options, while important in their respective contexts, do not directly pertain to the primary function of providing timely and safe air traffic management for the airport's operations. Ground handling services involve the physical management of aircraft on the ground but do not include air traffic control. Flight planning services are typically related to the preparation and filing of flight plans, which is distinct from the active management of air traffic in the airspace. Emergency management services are crucial in crisis situations but are not the primary duty of an air traffic control facility in routine operations.