Which of the following is traditionally the standard markup language used on the Web?

The standard markup language traditionally used on the Web is Hypertext Markup Language (HTML). HTML serves as the foundation for web pages, enabling the structuring of content such as text, images, links, and other multimedia elements. By utilizing various HTML elements, developers can organize their content into a hierarchical structure, which web browsers interpret and render for users.

While other choices like CSS and JavaScript are essential for web development, they serve different purposes. CSS (Cascading Style Sheets) is used for styling and layout, allowing developers to control the presentation of HTML elements. JavaScript is a programming language that enables interactivity and dynamic behavior on web pages. XHTML is a stricter version of HTML that adheres to XML syntax rules, but it is not as widely used as HTML in its traditional sense.

Thus, HTML is recognized as the core markup language for web development, making it the standard for creating structured web content.