How can smart sensors help save energy?

Correct answer: By automatically switching devices off when not in use

Smart sensors measure conditions such as movement, occupancy, temperature, light level or equipment status. The governing concept is demand-based automation: energy is supplied when a service is needed and reduced when it is not. For example, an occupancy sensor can switch off lights in an empty room, and a control system can place an idle device into a low-power mode. This lowers unnecessary electricity consumption without requiring constant manual checking. Thus, option B is correct. Keeping every device on continuously wastes energy, while polluting water and burning waste are harmful actions unrelated to sensor-based energy management. Sensors save energy through accurate detection and automatic control, not by damaging the environment.