What is defined as the ratio of energy radiated as light to the total energy radiated by a source?

is defined as the ratio of power input (in Watts) to the mean spherical candle power (MSCP) of a lamp.

In illumination engineering, the space-height ratio is defined as the ratio of:

Arrange the following lamps in the increasing order of their power rating and energy consumption required to provide the same level of illumination (based on their given efficacies): A. Incandescent Lamp with efficacy of 10 lumens/watt B. Compact fluorescent lamp (CFL) with efficacy of 60 lumens/watt C. Halogen lamp with efficacy of 20 lumens/watt D. Mercury vapour lamp with efficacy of 40 lumens/watt E. Light Emitting Diode (LED) lamp with efficacy of 80 lumens/watt Choose the correct answer from the options given below: