The correct answer is: A. data selector.
A demultiplexer is a device that takes one input signal and selects one of several output signals based on a control signal. It is also known as a data selector.
A multiplexer is a device that takes several input signals and selects one of them to be transmitted on a single output line. It is also known as a data distributor.
An encoder is a device that converts data from one form to another. For example, an encoder can convert a binary number to a decimal number.
None of the above is a correct answer.