You are presented with the question "How do you keep a cup hot?" and the following answer choices: 
- less water
 - electricity
 - heat energy
 - adding heat
 - energy usage
 - insulation
 - squeeze
 - energy

Now knowing that insulated material can be used for keeping warm and an insulated cup with a cover is great for keeping beverages warm, choose the best answer.


 

      insulation   