Fact 1: Some light bulbs convert electricity into light and heat energy.

Fact 2: Household light bulbs are evacuated glass enclosures with wires leading to a tungsten filament.

Given the two facts above, answer the question "Some what enclosures convert electricity into light and heat energy?" with the following options: 
- made
 - glass
 - wool
 - support
 - fabric
 - cotton
 - cells
 - unique


 

  glass       