What is magma? 

A)  It is molten rock. 
B)  It is an air pollutant given off by geothermal energy. 
C)  It is a deep source of fossil fuel. 
D)  It is a cooled lava flow.

Magma

Molten rock beneath the earth's surface that can form igneous rock when cooled.

Molten Rock

Rock that has been heated to a liquid state due to extreme temperatures, found beneath the Earth's surface or expelled during volcanic eruptions.

Geothermal Energy

Renewable energy derived from the natural heat of the earth's interior.