What is the protocol for transporting HTML documents across the Internet?

The correct choice is Hypertext Transfer Protocol (HTTP), which is specifically designed for transferring hypertext documents, such as HTML, across the Internet. HTTP enables web browsers and servers to communicate, facilitating the retrieval of web pages and other resources. When a user requests a web page, their browser sends an HTTP request to the server, which then responds with the requested HTML document. This process is fundamental to how the World Wide Web operates, making HTTP a cornerstone protocol for web communication.

While other protocols like FTP are used for transferring files, they do not specifically manage the transfer of HTML documents in the context of web browsing. Point-to-Point Protocol is primarily used for establishing a direct connection between two nodes, and Simple Mail Transfer Protocol is dedicated to sending emails, neither of which relates directly to the transport of web content like HTML. Thus, HTTP stands out as the appropriate protocol for the task in question.