The energy is measured in watt second, which is equal to a joule.
Both watt second or joules are the standard scientific unit of energy. Therefore, one kilowatt hour =( 1000 watt )(3600 seconds) =3.6*10^6 watt seconds of energy.
Normally we use kilowatt hour units as commercial the energy unit which is also written like 1Kwh and is equal to 3.6*10^6 watt second units of energy. Choose the option B.
I will answer with mathematical analysis:Work done(W) = Force x distance (Units N-mt or Kg-mt) = = F*x
The rate of doing work is called Power.Mathematically the derivative of Work done is Power.ie dW/dt = d(F*x)/dt = F*v
Units = N-m/sec = 1 watt.THe capacity of doing work is called Emergy.hence it is time dependent. Physically Work done and energy are same.dW=P*dt
Emergy =Powerxtime =watt-sec or biger unit KWh. Therefore Answer is B.