What happens during a phase change from a solid to a liquid?

1.The particles the solid vibrate faster and faster. After a while, they stop all motion.
2.The particles of the solid vibrate slower and slower. After a while, they stop moving.
3.The particles of the solid vibrate faster and faster. After a while, they can start to move around.
4.The particles of the solid vibrate slower and slower. After a while, they can start to move around.