All of the Following Statements Concerning Radiation as a Method

All of the following statements concerning radiation as a method of microbial control are true EXCEPT:

A) UV light effectively kills cells but does not penetrate surfaces well.
B) electron beams have a lot of energy but do not penetrate substances very well.
C) microwaves are valuable in microbial control only when they are used to heat food.
D) X rays are the most practical form of ionizing radiation for microbial control.
E) gamma rays penetrate substances well but require hours to kill microbes.