Telnet is a network protocol
Answer: option(a)
Step-by-step explanation:
Telnet is a protocol that allows the users to connect them with remote computers and it is by secured network. By installing the software of this protocol, you have access to connect and interact with remote computers.
Softwares like macOS, Windows, Linux, and Unix are built from this protocol named as Command-line telnet clients. Telnet protocol provides access to control remote computers using basic input and output commands.