The correct answer is D. Usenet.
Usenet is a worldwide distributed discussion system that was created in 1979. It consists of thousands of newsgroups, which are organized by topic. Users can read and post messages to newsgroups, and they can also subscribe to newsgroups to receive new messages automatically.
Usenet is a valuable resource for information and discussion on a wide variety of topics. It is also a great way to connect with people who share your interests.
Here is a brief description of each option:
- A. nicnet: A network that was created in the early 1980s to connect computer networks at research and education institutions.
- B. milnet: A network that was created in the early 1980s to connect military computer networks.
- C. telnet: A protocol that allows users to connect to remote computers and run programs on those computers.
- D. usenet: A worldwide distributed discussion system that was created in 1979.