What tag generates a horizontal rule or line break within text on a web document?

The tag that generates a horizontal rule or line break within text in a web document is the hr tag. This tag is specifically used to create a visual division or separation between sections of content, making it easier for users to distinguish between different parts of the information presented on a web page. The hr tag is an empty or self-closing tag, meaning it does not require an end tag to function.

In contrast, while the term "line tag" might suggest a function similar to the hr tag, there is no specific HTML tag called "line tag" that performs this function. The break tag (br tag) serves a different purpose—it is used to insert a line break but does not create a horizontal rule like the hr tag. The separator tag is also not a recognized HTML tag; it does not exist within standard HTML specifications. Therefore, the hr tag is the correct choice as it is explicitly designed to fulfill the requirement of creating horizontal rules in a web document.