What is CFL?
(A) Compact Fluorescent Lamp
(B) Compact Fluorescent Lamina
(C) Complete Fluorescent Light
(D) Controlled Fluorescent Light

Hint
We know CFL is an energy saving light which was designed so as to replace the incandescent light bulb which was highly power consuming.

Complete step by step answer
Fluorescent lamps are actually gas filled with electrodes at either ends.
When electricity is passed through the lamp, the electrons flow from one electrode to the other bumping into the mercury atoms in the gas and making it excited and the atoms that emit visible and ultraviolet light. The white coating of the glass absorbs the ultraviolet light and makes it more visible. This process is called fluorescence. As the coating stops the ultraviolet rays, it keeps the lamp from giving us cancer.
Hence, the correct option is (A), Compact Fluorescent Lamp.

Additional Information
There are few other types of lamps which work on the same principle but without a fluorescent coating as the gas filled inside mainly emits visible light.

Note
The other options also consisted of the terms Compact and Fluorescent but the final term decided the correct option. If we look at option (B), we see that the last word is lamina which literally means a stretched or an arched surface or in simple analogy, a plate. But that is not the CFL we are concerned about. Then comes the option (C) where the first word itself is irrelevant. Same is the case with option (D). The two words complete and controlled does not make any sense in this context.