What type of CSS selector is used to style elements after they are hovered over?

The choice of :hover as the correct answer highlights its specific purpose in CSS for enhancing user experience. This selector is designed to target elements when a user hovers their mouse pointer over them. This interaction can trigger visual changes, such as color changes, font adjustments, or other style modifications that give immediate feedback to the user.

The :hover selector is particularly useful for creating dynamic menus, buttons, or any interactive elements because it allows for a responsive design that reacts to user actions in real-time. This responsiveness helps in building engaging interfaces that guide users effectively through your web application.

The other selectors listed have distinct purposes that do not pertain to mouse interactions in the same way. For example, :focus is used when an element gains keyboard focus, typically through tabbing or clicking, rather than hover actions. :active applies styles to an element that is being activated, such as while a button is being clicked, and :visited targets links that the user has previously clicked on, altering their appearance based on browsing history rather than immediate mouse actions.