A perfectly reversible heat pump supplies to a building to maintain its temperature at 27°C. The cold reservoir is a river at 7°C. If work is supplied to the pump at the rate of 1 kW, at what rate does the pump supply heat to the building?
A. 15kW
B. 3.85kW
C. 1.35kW
D. 1.07kW
E. 1.02kW