You are presented with the question "What requires a source of electricity to produce light?" and the following answer choices: 
- 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.

Now knowing that aflashlight requires a source of electricity to produce light and flashlights provide the safest emergency lighting source, choose the best answer.


 

        An emergency lighting source. 