Fact 1: Irradiating food can be used to kill existing microorganisms in the food.

Fact 2: How Irradiation Works Food is irradiated using radioactive gamma ray sources, usually radioactive cobalt-60 or .

Given the two facts above, answer the question "Using radioactive gamma ray sources, existing microorganisms in food can be what?" with the following options: 
- killed
 - cancer
 - organisms
 - tiny
 - dangerous
 - extended
 - colored
 - resized


 

 killed        