Fact 1: Energy is used for heating a building by a heating system.

Fact 2: Geothermal energy is used for heating and cooling systems.

Given the two facts above, answer the question "What is a way to heat a building?" with the following options: 
- sound
 - Movement of an air mass
 - burning coal
 - static electricity
 - In the winter
 - potential energy
 - by indirect light
 - geothermal energy


 

        geothermal energy 