Which of the following layers of the OSI model is responsible for end-to-end encryption?

The presentation layer is primarily concerned with data translation, format conversion, and encryption/decryption of data for application layer use. While it can handle encryption tasks, it does not provide end-to-end encryption across a network; that responsibility lies with the transport layer.

The application layer serves as the interface for end-user services and applications, focusing on providing network services directly to user applications. It does not handle the end-to-end encryption itself; rather, it utilizes the transport layer protocols that implement such encryption to ensure secure communication.

The session layer manages sessions between applications, maintaining connections and controlling the dialogue between two systems. Although it can support the establishment of secure sessions, it is the transport layer that implements the actual end-to-end encryption needed to secure data during transmission.