Which protocol is considered an alternative to Telnet for secure data transfer?

SSH, or Secure Shell, is considered the alternative to Telnet for secure data transfer because it provides an encrypted connection between the client and the server. Unlike Telnet, which transmits data, including user credentials, in plain text, SSH ensures that all the communication is secure through encryption. This makes SSH a significantly safer choice for remote logins and command execution over unsecured networks, as it protects against eavesdropping, man-in-the-middle attacks, and replay attacks.

The other options do not serve as direct replacements for Telnet in the same context. HTTP, while used for secure web traffic, does not serve as a command-line interface tool like SSH. FTP is primarily used for file transfers and, in its basic form, does not encrypt data, though there are secure extensions such as FTPS and SFTP that do provide encryption. RDP is a protocol used for remote desktop access rather than a command-line interface protocol, placing it in a different category altogether.