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

Fact 2: Fiber optics works by carrying light along hair-thin filaments of glass.

Given the two facts above, answer the question "an incandescent light bulb converts electricity into light by sending electricity through what?" with the following options: 
- hair-thin molecules
 - hair-thin spokes
 - epidermis and dermis
 - hydrogen and oxygen
 - activation energy
 - an electron lens
 - hair-thin hairs
 - hair-thin fibers of glass


 

        hair-thin fibers of glass 