Answer
A. None of these
Explanation
Gamma rays are ionizing electromagnetic radiation, obtained by the decay of an atomic nucleus. Gamma rays are more penetrating, in the matter, and can damage living cells to a great extent. Gamma rays are used in medicine (radiotherapy), industry (sterilization and disinfection), and the nuclear industry.
Thus, gamma rays are used for all the options given in B - D. So the correct answer is option A. None of these
