Answer
A. None of these
Step-by-step 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