With reference to street- lighting, how do sodium lamps differ from LED lamps?1.Sodium lamps produce light in 360 degrees but it is not so in the case of LED lamps.2.As street-lights, sodium lamps have longer life span than LED lamps.3.The spectrum of visible light from sodium lamps is almost monochromatic while LED lamps offer significant colour advantages in street- lighting.Select the correct answer using the code given below

1. A

   3 only

   3 only. Statement 1 (360° sodium vs directional LED) also holds.

2. B

   2 only

   2 only. LEDs outlast sodium; the lifespan claim is backwards.

3. C

   1 and 3 only

   1 and 3 only. Sodium lamps throw light all around and are nearly monochromatic. LEDs are directional and give a broader, controllable colour. Sodium does not live longer.

4. D

   1, 2 and 3

   All three. Statement 2 fails.

Summary. Official key is (c) 1 and 3 only. High-pressure/low-pressure sodium is omnidirectional and almost one colour. LED street lights are directional and better on colour. LED life is longer, not shorter, than sodium.