Five Carnot engines operate between reservoirs with temperatures T_h and T_l as given below. Rank these engines according to their efficiency from most efficient to least efficient. If any of the engines have the same efficiency, give them the same ranking. Explain how you arrived at your rankings.
Engine A: T_h = 100°C; T_l = 0°C
Engine B: T_h = 250°C; T_l = 150°C
Engine C: T_h = 75°C; T_l = −25°C
Engine D: T_h = 300°C; T_l = 100°C
Engine E: T_h = 300°C; T_l = 0°C