Final answer:
Neon is the element used in advertising signs to create a reddish-orange glow when electrified, due to its stable and unreactive nature as a noble gas.
Step-by-step explanation:
The unreactive, gaseous element used in advertising signs for the bright reddish-orange glow it produces when an electric current is passed through it is Neon (Option B). Neon is a component of neon lamps and signs, and when you pass an electric spark through a tube containing neon at low pressure, you get the characteristic red glow that is often associated with 'neon' signs. The noble gases group, which includes neon, is known for its lack of reactivity and includes elements like helium, argon, krypton, xenon, and radon, all of which exhibit distinct glowing colors when electric currents pass through them. While pure neon is responsible for a reddish-orange light, the presence of other gases like argon or mercury vapor, or the use of colored glass tubes, can modify the color of the emitted light.