What type of Air Traffic Control service primarily deals with IFR traffic en-route?

Area Control Services are designed primarily to manage and coordinate IFR (Instrument Flight Rules) traffic that is in flight between various sectors or aerodromes, particularly when the aircraft are at cruising altitudes during their en-route phases. This service ensures safe separation between aircraft and provides navigation assistance as they travel through defined airspace, which is often managed on a regional basis.

While Aerodrome Control Services focus on managing aircraft operations during takeoff and landing at an airport, and Approach Control Services handle flights as they transition from en-route to landing, Area Control Services are specifically concerned with the en-route phase of flight. Flight Information Services, on the other hand, provide pilots with information about weather, navigational warnings, and other relevant data, but do not actively manage or control the movement of aircraft within controlled airspace. Thus, the focus of Area Control Services on en-route IFR traffic makes it the correct answer.