HTML and CSS Certification Practice Test

The <link rel="stylesheet"> element's primary function is to link an external CSS file to the HTML document, allowing the styles defined in that CSS file to be applied to the HTML content. This is crucial for separating the presentation layer from the content layer, which enhances maintainability and flexibility in web development.

When an external CSS file is linked, the browser fetches this file and applies the specified styles to the elements in the HTML document, facilitating consistent styling across multiple pages. This promotes an efficient approach to web design, as developers can manage styles in one central file instead of within the HTML structure itself, reducing redundancy and improving ease of updates.

In contrast, the other options do not accurately reflect the role of the <link rel="stylesheet"> tag. For instance, including JavaScript functionality involves using a different element, typically <script>, while creating a newsletter sign-up form requires input elements and form tags. Additionally, creating hyperlinks to other pages is accomplished using the <a> tag, not the <link> tag. Thus, the role of <link rel="stylesheet"> is clearly defined as connecting an external style sheet to the HTML document, making option B the correct choice.