For process 3→1 volume is constant ∴ Graph given in option (d) is wrong. And process 1→2 is adiabatic ∴ graph in option (1) is wrong ∵v= constant P↑,T↑ For Process 2→3 Pressure constant i.e.,P= constant ∴V↓T↓ Hence graph (c) is the correct V−T graph of given P−V graph