What is the coefficient of performance of an ideal heat pump that has heat transfer from a cold temperature of T_c to a hot temperature of Tₕ ?
A. {T_c}/{Tₕ - T_c}
B. {Tₕ}/{Tₕ - T_c}
C. {T_c}/{T_c - Tₕ}
D. {Tₕ - T_c}/{T_c}