Fact 1: An incandescent light bulb converts electricity into light by sending electricity through a filament.

Fact 2: An incandescent material is so hot that it glows, producing light.

Given the two facts above, answer the question "What happens when incandescent bulbs get hot" with the following options: 
- energy
 - They burn out
 - sunlight
 - They glow
 - heat energy
 - They explode
 - uncontrolled
 - They turn off


 

    They glow     