Ans A
Each time a mobile or portable cellular subscriber passes from one cell into another, the network automatically switches coverage responsibility from one basestation to another.
Each base-station transition, as well as the switching processor sequence itself, is called handoff.
In a properly functioning network, handoff occurs smoothly, without gaps in communications and without confusion about which basestation should be dealing with the subscriber.
Subscribers to a network need not doanything to make handoff take place, nor should they have to think about the process orabout which base station is dealing with the signals at any given moment.