Please answer ASAP!! How do we define energy efficiency?

А.) the ratio of the actual output energy to the input energy

B.) the ratio of power gain to power loss

C.) the product of input power and output power

D.) the sum of potential and kinetic energy

Air inially occupying a volume of 1 m2 at 100 kpa, 27 c undergoes three internally reversible processes in series. process 1-2 compression to 500 kpa during which pv constant process 2-3 adiabatic expanslon to 100 kpa process 3-1: constant-pressure expansion to 100 kpa (a) calculate the change of entropy for each of the three processes. (b) calculate the heat and work involved in each process. (c) is this cycle a power cycle or refrigeration cycle?