Fact 1: Insulated material can be used for keeping warm.

Fact 2: An insulated cup with a cover is great for keeping beverages warm.

Given the two facts above, answer the question "How do you keep a cup hot?" with the following options: 
- less water
 - electricity
 - heat energy
 - adding heat
 - energy usage
 - insulation
 - squeeze
 - energy


 

      insulation   