The unit for power in electricity should be watt. The power show how many energy transferred during a time and the SI unit would be joule per second.
The bill is charging for the amount of energy. The energy could be calculated by multiplying the power with time. In this case, the power in kilo watt will be multiplied by the duration in hour which make the kilowatt hour.
They are like that because they can't always be faulty and may have at least some spark of truth to this theory also as stated earlier a theory in scientific terms is just an observation so it can't really be turned down hence theory.
I’m pretty sure it’s B. Relative saying
What he said ^^. . . ....... . .
I think the answer is :extinct