Concept:Radiation is the only method of heat transfer that can pass through a vacuum without any material medium.
Explanation:Conduction needs a material medium because heat is passed by vibrating particles and collisions between neighbouring atoms.
Convection also needs a material medium because heat is carried by the bulk movement of fluids such as air or water.
Radiation does not need any medium because it transfers energy through electromagnetic waves, which can travel through empty space.
Diffusion is not a heat transfer method at all; it is the mixing of substances due to random particle motion.
Therefore, among the given options, only radiation matches the condition given in the question.
Answer:B. radiation