The correct answer is C. PPT.
A network protocol is a set of rules that allow computers to communicate with each other. SSH, HTML, and POP are all network protocols. PPT is not a network protocol. It is a presentation format created by Microsoft.
SSH (Secure Shell) is a cryptographic network protocol for operating network services securely over an unsecured network. SSH provides a secure channel over an unsecured network in a client-server architecture, connecting an SSH client application with an SSH server. Common applications include remote command-line login and remote command execution, but any network service can be secured with SSH.
HTML (HyperText Markup Language) is the standard markup language for creating web pages. It is a markup language, not a programming language. HTML is used to create the structure of a web page, and to add text, images, and other elements to the page.
POP (Post Office Protocol) is an Internet standard protocol for accessing email from a remote server. POP is a client-server protocol, which means that there is a POP client on the user’s computer and a POP server on the email server. The POP client connects to the POP server and downloads the user’s email messages. The user can then read the messages on their computer.