The Geothermal Gradient Tells Us That

The geothermal gradient tells us that:

A) The interior of the Earth is a source of heat, so temperature increases with depth.
B) The interior of the Earth is a source of heat, so temperature decreases with depth.
C) The Sun's energy is warming the interior of the Earth, so temperature increases with depth.
D) The Sun's energy is warming the interior of the Earth, so temperature decreases with depth.