Which CSS property is used to control the appearance of an element when it is hovered over by the mouse pointer?Optionshover-effectactive:hoveron-hover

To determine which CSS property is used to control the appearance of an element when it is hovered over by the mouse pointer, let's analyze the options provided:

1. hover-effect: This is not a standard CSS property; it appears to be a made-up term.

2. active: This is related to the state of an element when it is being activated (for example, when a button is being clicked), but it does not pertain specifically to hovering.

3. :hover: This is a pseudo-class in CSS that applies styles to an element when the mouse pointer hovers over it.

4. on-hover: This is also not a standard CSS property or pseudo-class.

Conclusion

The correct answer is :hover, which is used in CSS to define the styles of an element when it is being hovered over by the mouse pointer. For example:

element:hover {
    /* styles here */
}

This allows developers to create interactive effects that enhance user experience.