What is Point-to-Point Protocol (PTP) primarily used for?

Point-to-Point Protocol (PPP) is primarily used for establishing a direct connection between two networking nodes. It is most commonly associated with modem connections to the internet, where it facilitates the transmission of data over the telephone lines. PPP is designed to provide a standard method for transporting multi-protocol datagrams over point-to-point links, allowing for features like error detection, authentication, and configuration. Its widespread use in dial-up connections directly correlates with its purpose of managing the connection between a modem and an Internet Service Provider (ISP), making it the best answer for this question.

While other options may involve various network technologies, none of them directly represent the primary function of PPP in the context of establishing straightforward and efficient modem-based internet connections.