Establishing a Secure Terminal Connection

C.

The protocol used to establish a secure terminal to a remote network device is SSH (Secure Shell).

SSH is a protocol that provides a secure channel for remote login and command execution on a network device. It provides secure authentication, encryption, and integrity for data transmission over an insecure network. SSH is widely used in network administration, as it allows administrators to remotely manage network devices such as routers, switches, and servers.

In contrast, WEP (Wired Equivalent Privacy) is a security protocol used to secure wireless networks, but it is no longer considered secure and is susceptible to attacks. SMTP (Simple Mail Transfer Protocol) is a protocol used for email transmission, and it does not provide secure connections by default. IPSec (Internet Protocol Security) is a protocol used to secure network traffic by encrypting and authenticating IP packets, but it is typically used to secure site-to-site VPN connections rather than remote terminal connections.

Therefore, the correct answer is C. SSH.