A thermodynamic process is shown in the figure. The pressures and volumes corresponding to some points in the figure are P P = 3 10 Pa A 3 V = 2 10m A P = 8 10 Pa B V = 5 x 10 m. D B In process AB, 600 J of heat is added to the system and in process BC, 200 J of heat is added to the system. The change in internal energy of the system in process AC would be (a) 560 J (c) 600 J (b) 800 J (d) 640 J