The correct answer would be: El piloto
El piloto maneja el avión.
The pilot flies the plane.
El auxiliar de vuelo wouldn't be the correct answer since this means the flight attendant. The flight attendant is related to the plane since they help out and treat the passengers but they do not fly the plane.
Mi profesora de español also isn't the correct answer since this means the spanish teacher. She doesn't fly the plane since she is in charge of teaching spanish.
Lastly, El restaurante means the resturant and feeds people and doesn't fly the plane.
El piloto however means the pilot which is in charge of flying the plane.
Hope this helps! :3