Answer: The correct answer is diffusion.
Step-by-step explanation:
Boiling is a physical process in which a liquid gets converted into gas state at its boiling temperature.
Vaporization is a process in which a liquid gets converted into vapor phase.
Diffusion is a process in which a movement of substance takes place from a high concentration area to a low concentration area due to the random movement of the particles. Diffusion happens in gases and liquids because of the random movement of their particles.
Melting is a physical process in which a solid gets converted into liquid phase at its melting temperature.
Hence, the correct answer is diffusion.