Which of the following is a good definition of asynchronous communication?

A.
Low data transfer rate using only one channel for transmission

B.
High data transfer using many channels

C.
High-speed transmission controlled by electronic timing signals

D.
Sequential data transfer, using bits framed with start and stop bits

Explanation:
Asynchronous communication devices, like modems, must first agree
upon a communication rate. The communication is not synchronized in that the
devices involved can send data at will, sending a sequence of bits framed with start
and stop bits that are reassembled into data at the receiving end. Synchronous
communication devices, on the other hand, determine a synchronization scheme and
communicate data in a stream.