If energy efficiency is improved, the cost of energy would decrease and

-more coal would be available
-less electricity would be used
-homes would cost significantly less
-energy star appliances would no longer be necessary

The correct answer to the question is : B) Less electricity would be used.

EXPLANATION :

As per the question, there is increment in the energy efficiency.

Normally efficiency is defined as the ratio of output energy to the input energy .

As the efficiency is increasing, the electrical devices will give more output. Hence, there will be less loss of electricity in the form of other types of energy.

Due to the loss of energy due to various external factors like friction, heating effect, there was more consumption of electricity.

The increment in efficiency will reduce the consumption of electricity.

Hence, the correct answer to the question is less electricity will be used.