The Session Layer is primarily concerned with which of the following?

The Session Layer, which is the fifth layer in the OSI (Open Systems Interconnection) model, plays a critical role in managing sessions between applications. It is responsible for establishing, maintaining, and terminating conversations, or sessions, between two communicating endpoints. This includes the initiation of dialog, ensuring that both sides are synchronized and can communicate effectively, and gracefully ending a session when it is no longer needed.

This layer handles the control and management of the dialogue between applications, which can be either half-duplex or full-duplex, thereby coordinating when and how the data is exchanged. It ensures that the communication process operates smoothly and seamlessly, allowing applications to communicate over the network without interference or confusion.

The other options highlight functions that belong to different layers of the OSI model or to different purposes entirely. For instance, functions like encryption and decryption of data are handled at the Presentation Layer, data compression and formatting also reside there, while routing packets through the network is a function of the Network Layer. Thus, the focus of the Session Layer on managing dialog makes it distinct and essential in the context of network communication.