Which style rule would make the image 50% smaller during a hover?

<img id="photo" alt="" src="..." />

1.  img#photo:hover {scale: 0.5;}
2.  img#photo:hover {transform: scale(0.5);}
3.  img#photo {hover-scale: 0.5;}
4.  img#photo:hover {size: smaller;}

Correct Answer:

•  img#photo:hover {transform: scale(0.5);}