Answer:
Radiation
Step-by-step explanation:
Radiation.
It is by Radiation.
Conduction of heat is the process by which heat energy is transferred through a material, the average position of the particles of the material remaining the same. eg cloth, cork, wood etc.
Convection is the process by which heat is transferred in a liquid or gas by the actual movement of the heated fluid from the hotter to the colder parts.
Radiation is the process by which heat is transferred from a hotter to a cooler place with heating of the intervening medium.
Fusion(melting) is the process whereby a substance changes from solid state to a liquid state when heat is applied to it.