You are presented with the quiz "Using radioactive gamma ray sources, existing microorganisms in food can be what?" 

But you don't know the answer, so you turn to your teacher to ask for hints. He says that "irradiating food can be used to kill existing microorganisms in the food" and "how Irradiation Works Food is irradiated using radioactive gamma ray sources, usually radioactive cobalt-60 or ". 

So, what's the best answer to the question?


 

 killed          