Fact 1: Alight bulb is used for seeing in the dark.

Fact 2: Conventional light bulbs generate light by heating a filament.

Given the two facts above, answer the question "What is helpful for seeing in the dark?" with the following options: 
- an electron microscope
 - an electron lens
 - microscope
 - closing the blinds
 - blackouts
 - closing your eyes
 - focusing a lens
 - heating a filament


 

        heating a filament 