phy mc - electric energy cost

rice cooker --- 500W
that mean in 2 hours the rice cookers comsume 1kWh, that is $0.2 dallors.
similarly a 2000W heater consume 1 kWh at half an hour.
Therefore total fee : 0.5 * (10/2) + 0.5 * (10*2) = $12.5

D is the answer