Question type: Explain
Premise:
Conclusion:
I chose (B) thinking that the silencer will "share" the power with appliance. I realized that was just an assumption I made. It would actually not explain why the new silencing device will make lower electricity consumption because they are both using same power supply.
Anyways, I don't see why (A) is a correct answer. I'm not sure where to know that the motor's efficiency = electricity consumption