Ideal heat engine and power output

Curves AB and CD are isotherms; AD and BC are isochores.
An ideal heat engine uses 0.03 mole of an ideal gas and operates between a hot reservoir
at TH = 500 K and cold reservoir at TL = 320 K, in a cycle from A → B → C → D → A. From A → B
the gas undergoes an isothermal expansion, changing its volume from VA to 5.5VA . From B → C, the
pressure is reduced at a constant volume. From C → D, the gas undergoes an isothermal compression,
and from D → A, the pressure is increased at a constant volume until the gas is back at the original state
A.
If the engine operates at 55 cycles per second, the power output is:
A) 7.37 kW
B) 6.31 kW
C) 4.21 kW
D) 2.10 kW
E) 3.16 kW