Helium gas is compressed steadily from 90 kPa and 25°C to 800 kPa at a rate of 2 kg/min by an adiabatic compressor. If the compressor consumes 80 kW of power while operating, the isentropic efficiency of this compressor is
(a) 54.0%
(b) 80.5%
(c) 75.8%
(d) 90.1%
(e) 100%