You are presented with the quiz "What prevents cold food from growing poisonous bacteria?" 

But you don't know the answer, so you turn to your teacher to ask for hints. He says that "arefrigerator is used for keeping food fresh for a long period of time" and "to prevent bacterial food poisoning, the basic rule is to keep hot foods hot and cold foods cold". 

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


 

     refrigerators      