An ideal-gas mixture of helium and argon gases with identical mass fractions enters a turbine at 1200 K and 1 MPa at a rate of 0.3 kg/s, and expands isentropically to 100 kPa. The power output of the turbine is
(a) 478 kW
(b) 619 kW
(c) 926 KW
(d) 729 kW
(e) 564 kW