Which of the following does NOT belong to the category of energy-efficient lighting?

The option that does not belong to the category of energy-efficient lighting is Metal Halide.

Metal Halide lamps are typically used for applications like outdoor lighting and industrial spaces, but they are less energy efficient compared to other options listed. They consume more energy to produce light and also have a shorter lifespan, meaning they need to be replaced more frequently.

On the other hand, LED (Light Emitting Diode) lighting is known for its high energy efficiency, lasting lifespan, and lower energy consumption compared to traditional lighting solutions. Low Pressure Sodium and High Pressure Sodium lamps, while they do provide substantial light output and are commonly used for street and outdoor lighting, are still considered more energy-efficient options than Metal Halide lamps, particularly because they are designed for longer operational life and lower wattage consumption. Hence, Metal Halide stands out as the least energy-efficient option among those listed.