Final Answer:
Handoff is a term used to transfer radar identification of an aircraft to another controller for the purpose of coordinating separation action. Option A is the answer.
Step-by-step explanation:
Handoff (Option A) in air traffic control refers to the process of transferring the responsibility for monitoring and controlling an aircraft from one controller to another. This transfer includes the radar identification of the aircraft, allowing the receiving controller to continue providing safe and efficient separation services.
The term is crucial in ensuring the seamless management of aircraft within controlled airspace. Options B, C, and D (Radar sweep, Beacon transfer, and Altitude adjustment) are not directly associated with the transfer of radar identification between controllers in the context of air traffic control.
Option A is the answer.