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

Fact 2: Insulation is a material with the ability to store heat.

Given the two facts above, answer the question "the ability to store what can be used for keeping warm" with the following options: 
- lipids
 - fats
 - knowledge
 - water
 - energy
 - fur
 - data
 - heat


 

        heat 