Evaluations for input

A gas-turbine power plant operates on the simple Brayton cycle between the pressure limits of 100 and 1600 kPa.The working fluid is air, which enters the compressor at 40°C at a rate of 850 m^3/min and leaves the turbine at 650°C. Using variable specific heats for air and assuming a compressor isentropic efficiency of 85 percent and a turbine isentropic efficiency of 88 percent, determine (1) the net power output and (2) the back work ratio.<image 1>

(A) (1) 6001 kW, (2) 0.436

(B) (1) 6181 kW, (2) 0.536

(C) (1) 6081 kW, (2) 0.536

Answer with the option's letter from the given choices directly. No punctuation.