Which of the following terms refers to the process in which headers and trailers are added around user data?

Encapsulation is the fundamental networking concept in which each protocol layer adds its own control information (header and, in some layers such as Data Link, a trailer) around the data received from the layer above. This process occurs at every layer of the OSI model as data travels from the application layer down to the physical layer, enabling proper addressing, error checking, and delivery at each layer.

Authentication is the process of verifying the identity of a user or device, which has nothing to do with adding headers and trailers to data.

Authorization determines what resources or actions an authenticated entity is permitted to access, not the packaging of data for transmission.

Encryption transforms plaintext data into ciphertext to ensure confidentiality, which is distinct from the structural wrapping of data with headers and trailers.