Correct Answer: Argon

Solution : The correct option is Argon.

Argon gas is found in many light bulbs, notably incandescent lamps. Argon is frequently used as a filler gas in incandescent bulbs to create a low-oxygen environment that prevents the filament from oxidizing and burning out. The inclusion of Argon gas contributes to the bulb's longevity and efficiency by lowering filament evaporation.