You are presented with the question "How can heat be kept?" and the following answer choices: 
- an electric stove
 - exposed material
 - insulated material
 - hydration
 - permeable material
 - electricity
 - wet material
 - In the winter

Now knowing that insulated material can be used for keeping warm and sunlight heats the ground, warming it up, choose the best answer.


 

   insulated material      