Answer:
9 kW-hr
Explanation:
3000 W = 3 kW for 1 hr = <u>3 kW - hr </u>
2000 W = 2 kW for 3 hr = <u> 6 kW -hr</u>
<u />
total power = <u> 3 + 6 = 9 kW-hr</u>
To solve the problem it is necessary to refer to the definition of entropy.
Entropy is defined aso

Where,
Heat exchange
T = Temperature
Since the heat exchange is conserved and it is an isothermal process where the temperature remains constant the change in entropy remains the same, ie
(Reamins same)
Therefore the correct answer is C.
Conductors transfer energy (metal is a good one) and insulators stop the transfer of energy (such as rubber or plastic). Sorry if that is wrong, but I hope it helps!