Which of the following is the correct German word for "filament"?

The correct answer is "Heizfaden," which directly translates to "filament" in German, particularly in the context of electrical filaments used in bulbs or heating elements. In technical language, a "Heizfaden" refers specifically to the thin wire or material that emits light or heat when an electric current passes through it, similar to how a light bulb filament operates.

The other choices do not accurately correspond to the word "filament" in this context. "Leiter," for instance, translates to "conductor," which refers to materials that allow the flow of electric current but does not encapsulate the specific function of a filament. "Vorrichtung," which means "device" or "apparatus," is too broad and does not convey the specificity of a filament. Lastly, "Draht" means "wire" and, while related, does not specify the use of that wire as a filament in electrical applications. Therefore, "Heizfaden" is the most appropriate and precise term for "filament" in this context.