Both bus and tree topologies are characterized by the use of multipoint （） . For the bus, all stations attach, through appropriate hardware （） known as a tap, directly to a linear transmission medium, or bus. Full-duplex operation between the station and the tap allows data to be transmitted onto the bus and received fromthe （） . A transmission from any station propagates the length of the medium in both directions and can be received by all other （） . At each end of the bus is a （） , which absorbs any signal, removing it from the bus.
Both bus and tree topologies are characterized by the use of multipoint（）.
A．medium
B．connection
C．token
D．resource
