In this task, you are given a multiple-choice question and you have to pick the correct option. Answer with option indexes (i.e., "A", "B", "C", and "D").

Tungsten is a metal which is found in large amounts in filaments, which are used in incandescent light bulbs. These light bulbs work because (A) light bulbs get very warm (B) filaments are able to freeze (C) the filament glows warmly (D) the filament catches fire
C