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. Given these facts, what prevents cold food from growing poisonous bacteria among the following options:
- Dehydration
 - Cooking
 - a hydraulic system
 - sweating
 - refrigerators
 - fur and fat
 - an electric stove
 - hard outer covering


 

     refrigerators    