You are presented with the question "What used for keeping food fresh for a long period of time?" and the following answer choices: 
- cooled
 - viruses
 - Energy
 - heat
 - Winter
 - bacteria
 - cold
 - phytoplankton

Now knowing that arefrigerator is used for keeping food fresh for a long period of time and people consume foods that are cold from refrigeration, choose the best answer.


 

       cold  