Explanation:

- The Earth's atmosphere is primarily composed of nitrogen and oxygen, with nitrogen making up about 78% and oxygen around 21%.

- Argon is the third most abundant gas. It constitutes about 0.93% of the atmosphere.

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- Option 1: 1%

- This is not correct because argon is just under 1% of the atmosphere. It's close, but slightly higher than the actual concentration.

- Option 2: 2%

- This is incorrect, as argon doesn’t make up 2% of the atmosphere.

- Option 3: 3%

- This is incorrect, as it significantly overestimates argon's presence in the atmosphere.

- Option 4: 4%

- This is incorrect, as it is even higher than option 3 and not accurate for argon's contribution.

- Correct Answer: Option 1: 1%

- Argon’s actual contribution is around 0.93%, closest to 1% listed.

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