Which protocol is primarily used for securely transferring files over the Internet?

The correct choice is SFTP, which stands for Secure File Transfer Protocol. This protocol is specifically designed to provide a secure method for transferring files over the Internet. It achieves security by using encryption to protect the data being sent, ensuring that sensitive information remains confidential and safe from unauthorized access during transmission.

SFTP operates over a secure shell (SSH) connection, which adds an additional layer of security compared to traditional FTP (File Transfer Protocol). This means that all file operations are protected against eavesdropping and man-in-the-middle attacks, which are significant risks in unencrypted data transfers.

Other protocols mentioned have different primary purposes. FTP, for instance, is used for file transfers but does not include any inherent security features, making it vulnerable to data interception. TCP (Transmission Control Protocol) is a foundational transport layer protocol that ensures reliable delivery of data segments but does not specifically address file transfer on its own. SNMP (Simple Network Management Protocol) is used for monitoring and managing network devices, rather than for transferring files.

Thus, SFTP is the best choice for securely transferring files due to its encryption capabilities and the use of secure channels.