The correct answer is B. 22 kW.
The power factor is a measure of how efficiently the energy in an AC circuit is being used. A power factor of 0.8 lagging means that the circuit is using 80% of the energy it is receiving, and the other 20% is being wasted as heat.
The apparent power in an AC circuit is the product of the voltage and current. The real power is the product of the voltage and current times the power factor.
In this case, the apparent power is 40 kVA, and the power factor is 0.8 lagging. The real power is therefore 40 kVA x 0.8 = 32 kW.
Option A is incorrect because it is the power factor, not the power.
Option C is incorrect because it is the apparent power, not the power.
Option D is incorrect because it is twice the real power.