The Current Practice of Geothermal Power Generation May Not Always

The current practice of geothermal power generation may not always provide a practical renewable energy source because ___________

A) in some instances, pollution emissions can be very high
B) in some cases, the heated groundwater is used much faster than it is recharged
C) geologically heated groundwater is unsuitable for these plants and must be purified first
D) in many cases, the magma is used faster than it is recharged
E) power plants have high maintenance costs