Which protocol is commonly used to secure communications over the internet?

The reason C, HTTPS, is the correct answer is that it is specifically designed to secure communications over the internet by using encryption. HTTPS stands for Hypertext Transfer Protocol Secure and combines HTTP (which is used for transferring web pages) with additional security layers, usually through the use of SSL/TLS (Secure Sockets Layer/Transport Layer Security). This encryption ensures that all data exchanged between the client (such as a web browser) and the server is secure, protecting it from eavesdropping, tampering, and other forms of cyber threats.

In contrast, HTTP is the standard protocol for transmitting data over the web but does not include any encryption, making it vulnerable to interception. FTP (File Transfer Protocol) is commonly used for file transfers but lacks built-in security features. Telnet is a protocol used for remote access to devices over a network, but like HTTP, it transmits data in plaintext and is not secure for sensitive communications. Thus, HTTPS is the preferable choice when security is a priority in internet communications.