Radiation is energy emitted or transmitted as particles or waves.

• A. Heat
• B. Matter
• C. Radiation
• D. Sound

Answer: (C)

Radiation refers to energy that is emitted or transmitted as waves or particles, such as light, X‑rays, or radioactive particles. That makes it the best fit because it specifically describes the mechanism of energy transfer itself—how energy moves from a source without needing a medium in some cases (like light traveling through vacuum) or as particles in others. Heat, while related, is a form of energy transfer arising from a temperature difference and can be moved by radiation, conduction, or convection, so it isn’t defined strictly as energy emitted as waves or particles. Matter is physical substance, not energy transfer, and sound is a mechanical wave that requires a medium to propagate, not energy transmitted as electromagnetic waves or particles. So the statement aligns precisely with the concept of radiation.