Concept:The electromagnetic spectrum is arranged by frequency, with higher frequency meaning shorter wavelength.
Explanation:From low to high frequency, the common order is: radio waves, infrared rays, visible light, ultraviolet rays, X-rays, and gamma rays.
Among the options given, gamma rays are not listed.
X-rays have the highest frequency of the four listed waves.
Radio waves have the lowest frequency, followed by infrared rays, then ultraviolet rays.
Therefore, X-rays are the correct choice.
Answer:C. X-rays