A cyclic heat engine receives 600kJ of heat from a 1000 K source and rejects 450 kJ to a
300 K sink. The quantity $\oint dQ/T$ and efficiency of the engine are respectively
(a) 2.1 KJ/K and 70% (b) - 0.9 kJ/K and 25%
(c) + 0.9 kJ/K and 70% (d) - 2.1 kJ/K and 50%