You are presented with the quiz "Irradiating food can be used to kill what in the food?" 

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 "fermentation occurs through the action of microorganisms in the large intestine". 

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


 

   Something that causes fermentation        