Final answer:
The gaseous element used in advertising signs that produces a bright, reddish-orange glow when an electric current is passed through it is neon (Option A).
Step-by-step explanation:
Neon is the unreactive, gaseous element that emits a bright, reddish-orange glow used in advertising signs when electrically excited. The gaseous element used in advertising signs that produces a bright, reddish-orange glow when an electric current is passed through it is neon.
Neon gas, when contained in a tube at low pressure and subjected to an electric spark, emits the signature red light commonly seen in neon signs. Although some signs may use other noble gases such as argon, krypton, or mixtures of gases to achieve different colors, the distinctive reddish-orange light is characteristic of neon gas alone.
Thus, the correct option is A.