Aflashlight requires a source of electricity to produce light, and flashlights provide the safest emergency lighting source. Given these facts, what requires a source of electricity to produce light among the following options:
- Broken light bulb.
 - The sun.
 - basic building blocks of life
 - an electron microscope
 - The source magazine.
 - algae and plants
 - the simplest of green plants
 - An emergency lighting source.


 

        An emergency lighting source. 