Ground-source heat pumps use the difference in temperature between the air and soil to warm and cool buildings. The upper 10 ft of the Earth is always at a constant temperature of , which is ideal for warming buildings in the winter and cooling them in summer.

Which best describes the first law of thermodynamics as compared to the second law of thermodynamics? a. the first law describes how thermal energy is conserved but not the direction it moves. b. the first law describes the direction thermal energy moves but not how it is conserved. c. the first law describes how thermal energy can be created but not how it can be destroyed. d. the first law describes how thermal energy can be destroyed but not how it can be created.