This home system illustrates the use of

The answer should be C) geothermal energy.

If this is the appropriate description of the home:

A home located next to a 5-acre pond (30 feet deep in the center) uses the steady temperature of the deep pond water for heat exchange. A closed system of water is piped from the home underground to deep regions of the pond and then back to the home. Inside the home, a heat exchange system extracts heat in the winter and removes heat from the home in the summer. This home relies completely on electricity, generated by burning coal at a distant power plant.