Which protocol is commonly used for secure communication over the internet?

The option that indicates the correct protocol for secure communication over the internet is HTTPS (Hypertext Transfer Protocol Secure). HTTPS extends HTTP by adding a layer of security using SSL (Secure Sockets Layer) or TLS (Transport Layer Security) protocols. This encryption ensures that data exchanged between a user's browser and the website remains private and secure from eavesdroppers and attackers.

In contrast, the other protocols listed do not inherently provide secure communication. FTP, for instance, is used for transferring files but does so without encryption, which exposes any data sent over the network. HTTP also facilitates communication on the web but does not include security measures, making it vulnerable to attacks such as man-in-the-middle. Lastly, SMTP is primarily used for sending emails and does not include built-in encryption for securing messages during transmission. Hence, HTTPS is essential for any sensitive data transmission over the internet.