A.
High heat is the source of most of the geothermal energy but low heat groundwater is also used sometimes.
B.
Even though low temperatures are possible, high heat is the best resource for energy production for groundwater.
C.
Both high heat and low heat sources are used for the production of geothermal energy from groundwater.
D.
Most high heat sources for geothermal energy are tapped from applications that involve low heat in groundwater.