Which protocol is used for secure communication over a computer network?

The correct choice is HTTPS, which stands for Hypertext Transfer Protocol Secure. This protocol is an extension of HTTP and adds a layer of security on the data in transit by using encryption protocols such as SSL (Secure Sockets Layer) or TLS (Transport Layer Security). This encryption ensures that the communication between a user's web browser and the web server is private and secure, preventing eavesdropping, tampering, or man-in-the-middle attacks.

HTTPS is commonly used for secure transactions on the internet such as online banking, shopping, and any activity that requires the exchange of personal information. By using HTTPS, websites can verify their identity to users and encrypt the data they share, thereby maintaining confidentiality and trust.

In contrast, the other options lack the necessary security measures provided by HTTPS. HTTP does not provide encryption, making it vulnerable to interception. FTP (File Transfer Protocol) is primarily used for transferring files and doesn’t incorporate encryption in its basic form. Similarly, SMTP (Simple Mail Transfer Protocol) is intended for sending emails and does not provide security for data in transit unless used with additional security protocols like SMTPS.