The exercise is about filling in the gaps and is related to the History of the ARPANET.
From the text:
In 1972, earlier designers built the ARPANET connecting major universities. They broke communication into smaller chunks, or packets and sent them on a first-come, first-serve basis. The limit to the number of bytes of data that can be moved is called line capacity, or bandwidth.
When a network is met its capacity the user experiences unwanted pauses. When the network is "slowing down", what is happening is users are waiting for their packet to leave the queue.
To make the queues smaller, developers created mixed packets to move simultaneously.
Learn more about the ARPANET at:
https://brainly.com/question/16433876