What are geothermal heat pumps used for?
a. cooling and heating buildings
b. cooling buildings
c. heating buildings
d. heating water for using in homes

Heat pumps are also known as refrigeration units for heating and cooling homes by taking heat from air outside in the winter time and then reversed to take heat out of the inside of a home in the summertime. The Geothermal heat pumps take heat from the ground by way of buried pipes deep in ground with chemicals such as water and glycol or similar and transfers that heat into homes in the winter time.
Heating buildings

The magnets would be | n s | and | s n|

If its history of, then b) because a) implies only present day (now)