Which of the following is a form of secure protocol for FTP?

SFTP stands for Secure File Transfer Protocol. It is an extension of the SSH (Secure Shell) protocol and is designed specifically for secure data transmission over a network. SFTP encrypts both the commands and the data, which prevents sensitive information from being exposed during the transfer process. This makes it a robust choice for secure file transfer compared to traditional FTP, which transmits data in plaintext and is thus vulnerable to interception and attacks.

The other options listed do not serve the same purpose as a secure protocol for FTP. SOCKS is a general-purpose proxy protocol that facilitates communication between a client and a server through a proxy server, primarily focused on creating a secure communication channel rather than file transfer. HTTP is a protocol used for transmitting hypertext and is also not secure by default, although HTTPS (HTTP Secure) is a secure version of HTTP. SCMS (Serial Copy Management System) is a digital rights management method that controls copying of audio recordings and is not related to file transfer protocols.