What is the primary function of Air Traffic Control (ATC)?

The primary function of Air Traffic Control (ATC) is to direct air traffic and communicate with aircraft. This involves monitoring and guiding the movement of aircraft both in the air and on the ground, ensuring safe distances between planes, providing instructions for takeoffs and landings, and facilitating efficient routes for flight operations. ATC personnel communicate critical information to pilots, such as altitude changes, approach vectors, and potential airspace hazards, to maintain a safe and orderly flow of air traffic. This role is vital for preventing collisions, minimizing delays, and ensuring safety in the increasingly busy skies.

The other options relate to important aspects of aviation but do not capture the essence of ATC's primary responsibilities. Managing ticket sales is a function typically handled by airlines, weather updates are provided by meteorological services, and airport security protocols fall under the jurisdiction of security agencies rather than ATC. Therefore, the answer that identifies ATC's main function effectively encapsulates its essential role in the aviation ecosystem.