Concept:Heat transfer without a material medium occurs through electromagnetic waves, known as radiation.
Explanation:Radiation does not require particles or a medium to travel.
It can pass through empty space or a vacuum.
The Sun's heat reaches Earth through radiation across space.
Radiation involves emission of energy as electromagnetic waves.
Examples include light, radio waves, and microwaves.
Conduction and convection both require a material medium.
Diffusion is not a method of heat transfer at all.
Therefore, radiation is the correct method.
Answer:D. Radiation