What information is part of the encapsulation done at the network interface layer?

The encapsulation at the network interface layer, also known as the data link layer, primarily involves the addition of information that allows devices on the same local network segment to communicate effectively. At this layer, the source and destination MAC (Media Access Control) addresses are crucial, as they identify the physical devices on the local network. Each device on the Ethernet network has a unique MAC address, and this addressing helps in routing the frames from one device to another within that local network segment.

In contrast, the other choices pertain to different layers of the OSI model. Source and destination IP addresses are related to the network layer (Layer 3), where routing through different networks occurs. Source and destination port numbers are associated with the transport layer (Layer 4), which handles communication between applications on devices. Lastly, source and destination email addresses are part of application layer protocols, primarily for email communication, and do not play a role in the encapsulation process relevant to the network interface layer. Thus, including MAC addresses in encapsulation at the network interface layer is essential for facilitating local area network communications.