Geothermal energy is an alternative energy source. however, it is not resourceful enough to replace more than a minor amount of the earth's energy needs. why is this?
a. drilling through the earth to reach areas hot enough to create steam is possible, but very expensive and difficult.

b. once the cool water is poured down the well and filters through the rocks, the rocks cool off and are no longer hot enough to turn water into steam.

c. there are only a few places where the earth's core is hot. it is cool in places like antarctica.

d. the center of the earth is not hot enough to make a significant energy contribution.