Which of the following is an example of a Peer-to-Peer (P2P) use case?

The peer-to-peer (P2P) model is characterized by the way each participant in the network (or peer) can act as both a client and a server. This model allows for direct sharing of resources and data among users without needing a centralized server to manage the interactions.

In the case of using torrents for downloading files, this method exemplifies P2P because it allows users to download pieces of files directly from one another. Each user not only downloads data but also uploads pieces of files they have already downloaded, contributing to the sharing process. This decentralized approach increases efficiency in sharing large files and distributes the bandwidth load among all users, reducing the reliance on a central server.

The other options represent scenarios where a central server is pivotal in facilitating communication or data exchange, which is contrary to the P2P model. In online gaming with centralized servers, for example, the server manages the game environment and player interactions. Similarly, direct messaging in social media typically relies on central servers to route messages, and video conferencing software often requires centralized infrastructure to manage connections between participants. Thus, torrents distinctly illustrate the principles of a P2P use case effectively.