Which answer best explains what happens to particles as their temperature rises?

Heat is a form of energy. As heat is added to a substance, the particles gain more energy, which becomes kinetic energy (energy of motion). This cause the particles to move and vibrate faster. The more heat, and therefore the more kinetic energy and more speed, that is added to a substance, the easier it is for particles to break free from it's state and evaporate.

Particles are always vibrating, as temperature rises, thermal energy is being released into the particles, so they start vibrating faster in order for them to release the thermal energy.