Explanation:

- Option 1: Helium

- Helium is a rare gas, but it is not the most abundant in the Earth's atmosphere.

- It is the second lightest element and often used in balloons.

- Option 2: Neon

- Neon is present in trace amounts and is less abundant than other noble gases in the atmosphere.

- Known for its bright glow in signs, it's still not the most abundant.

- Option 3: Xenon

- Xenon is a rare gas that's quite scarce in the atmosphere.

- It's used in specialized lighting and as an anesthetic.

- Option 4: Argon

- Argon is the correct answer, as it is the most abundant noble gas in the atmosphere.

- It makes up about 0.93% of the Earth's atmosphere.

- Used in welding and preserving historical documents due to its inert properties.