What occurs without direct contact between two substances?

Radiation is the correct answer because it describes the transfer of energy in the form of electromagnetic waves, which can occur without the need for direct contact between substances. This process allows energy to be transferred through a vacuum or in a transparent medium and is how the sun's heat reaches the Earth.

In contrast, conduction involves the direct transfer of heat through contact between materials, where thermal energy moves from the hotter object to the cooler one. Convection requires the movement of fluid (liquid or gas) to transfer heat, which also depends on contact between the fluid and the surfaces it interacts with. Evaporation is a surface phenomenon seen in liquids where molecules at the surface gain enough energy to enter the gas phase; while it also does not require direct contact with another substance, it involves individual molecules escaping into the atmosphere, rather than radiative heat transfer. Thus, radiation is unique in its ability to transfer energy across distances without the necessity for material contact, making it the correct choice.