X-ray photons are the bundles of energy that travel as electromagnetic radiation.

• A. Protons
• B. Photons
• C. Molecules
• D. Neutrons

Answer: (B)

Photons are the bundles of energy that travel as electromagnetic radiation. In the x-ray range, light exists as individual photons that move at the speed of light. Each photon carries a quantum of energy proportional to its frequency (E = hν), so higher-frequency X-rays have more energy. Protons, molecules, and neutrons are matter particles or composites and do not serve as the energy quanta of electromagnetic radiation. They are not the discrete energy packets that make up light, which is why photons are the correct answer.