A closed system receives 200 kJ of heat at constant volume. It then rejects 100 kJ of heat while 50 kJ of work is done on it at constant pressure. If an adiabatic process restores the system to its initial state, the work done by the system during this process is
(1) 100 kJ
(2) 50 kJ
(3) 150 kJ
(4) 200 kJ