When you use an external style sheet with an HTML document, you get all but one of the benefits that follow. Which one is it?

Your HTML files are smaller and simpler

Your CSS files are smaller and simpler

You provide consistent formatting for all of the pages that use the style sheet

You can modify the formatting for all of the related pages by changing one style sheet

Your CSS files are smaller and simpler.

Explanation:

External stylesheet are used in HTML pages to keep the HTML content and its styling separate. When using external stylesheet all the style rules are defined in CSS files and HTML files only contain the HTML code.

By using external style sheet,

One can make HTML code smaller and simpler. One can use the same stylesheet in multiple HTML pages and thus provide styling to multiple pages. With external stylesheet one can alter the single stylesheet code and its effect can be seen on all pages which are using that stylesheet.

Using external stylesheet has no effect on the content of CSS files. The CSS files will contain the same CSS style rules that are defined for any HTML page within the page.

Thus using external stylesheet doesn't make CSS files smaller and simpler.