Which of the following rays has the least wavelength?

ANS:C - Cosmic rays

Among the options provided, cosmic rays typically have the shortest wavelengths. Cosmic rays consist of highly energetic particles, such as protons, electrons, and atomic nuclei, that travel through space at nearly the speed of light. These particles can have wavelengths ranging from extremely short gamma rays to longer wavelengths approaching the range of X-rays. While X-rays also have very short wavelengths, cosmic rays can have even shorter wavelengths because they include particles with energies far greater than those typically produced in X-ray machines. Therefore, cosmic rays generally have the least wavelength among the options listed.