【单选题】A large horizontal axis wind turbine operating at the design wind speed will take about half the energy from the wind. Why can it not take all the energy from the wind?
A.
Most of the air escapes through the space between the blades
B.
Some of the wind bounces back off the blades and is unable to pass through the machine
C.
The wind must be left with enough kinetic energy to exit the turbine
D.
The wind turbine has the same thermodynamic efficiency as a combustion engines