The coloured discharge tubes for advertisement mainly contain

Answer: Option D

Neon gives a distinct reddish-orange glow when used in either low-voltage neon glow lamps or in highvoltage discharge tubes or neon advertising signs. The red emission line from neon is also responsible for the well known red light of helium-neon lasers. Neon is used in a few plasma tube and refrigerant applications but has few other commercial uses.