How can you change the color of a link when the mouse hovers over it?

The correct approach to change the color of a link when the mouse hovers over it is to use the selector that targets anchor tags, specifically the pseudo-class for hover. The notation 'a:hover' is ideal because 'a' selects all anchor elements, and ':hover' applies the specified styles when the mouse pointer is over those elements. Thus, when you set 'color: green;' under this selector, it effectively changes the text color of the link to green during the hover state, providing a clear visual indication to the user.

Other options do not achieve the desired effect. The option 'link:hover' is incorrect as 'link' is not a valid CSS selector; it should be 'a' to denote anchor tags. Similarly, 'link:focus' applies styles when an anchor tag or input element is focused, not when it is hovered over. Lastly, 'a:visited' styles links that have already been visited and does not relate to hover actions. Overall, 'a:hover' precisely targets the interaction needed for changing link colors on hover.