Aclimate-control heat pump can both heat and cool a building by

a. moving heat energy from a low-temperature source to a
high-temperature sink.
b. moving heat energy from a high-temperature source to a
low-temperature sink.
c. moving heat energy either from a low-temperature source to a
high-temperature sink, or from a high-temperature source to a
low-temperature sink.
d. moving heat energy either from a low-temperature source to a
low-temperature sink, or from a high-temperature source to a
high-temperature sink.