What indicates heat transfer through radiation?

Heat transfer through radiation is characterized by the transfer of energy via electromagnetic waves. Unlike conduction, which requires direct contact between molecules, or convection, which involves the movement of fluids (liquids or gases), radiation allows energy to be transferred through a vacuum or clear space. This process is evident when, for example, the sun warms the Earth's surface; energy from the sun travels through the vacuum of space in the form of electromagnetic radiation.

Radiation does not rely on the presence of matter to propagate, which distinguishes it from other forms of heat transfer. This principle is crucial in understanding how thermal energy moves in scenarios where no medium is present, such as in outer space, or how objects can emit and absorb infrared radiation. Hence, the correct answer effectively captures the essence of radiation as a mode of heat transfer through electromagnetic waves.