Assertion: Kilowatt-hour is the unit of energy.
Reason: One kilowatt hour is equal to `3.6 xx 10^6 J`.
Options:
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false and R is also false.