Answer:
PCM encoded samples from 24 voice band channels
Step-by-step explanation:
The Multiplexer from a lot of inputs generates one single output. And it is the select line that determines which of the input is going to influence output. And the select lines determine the increase in the quantity of data that can be sent through the network in a given amount of time. And this is termed as a data selector. Please note, this is application of multiplexer in data transmission.
And now coming to the T1 carrier system, it is a time division multiplexor, which multiplexes the PCM encoded samples coming from 24 band channels that require to be transmitted over an optical fiber or single metallic wire pair. And for this question, we need what is being multiplexed, and that is as mentioned in the Answer section.