What is a simple way to conserve energy?

Correct answer: Switching off lights when not needed

The governing concept is energy conservation: providing the same useful service while avoiding unnecessary energy consumption. Switching off lights when they are not needed directly prevents electricity from being wasted, so option B is correct. Leaving lights on during daylight, running a fan in an empty room, and keeping unused devices switched on all consume energy without providing a useful benefit. Such small actions can reduce electricity demand, lower household expenses, and indirectly reduce emissions when electricity is generated from fossil fuels. Good conservation habits include using daylight, switching off appliances, and unplugging equipment when appropriate. The key test is whether the action prevents avoidable use.