Noble gases are unreactive elements in Group 0 of the Periodic Table.

Steps:

• Identify the groups in the shown Periodic Table section; unreactive gases are in Group 0 (noble gases).
• Recall that noble gases have full outer electron shells, making them stable and unreactive.
• Check which option is in Group 0 and exists as a gas at room temperature.
• Confirm its presence in Earth's atmosphere (e.g., argon is about 0.93%).

Why D is correct:

• D represents argon (Ar), a Group 0 noble gas with a full outer shell (18 electrons), rendering it chemically unreactive, and it comprises nearly 1% of the atmosphere.

Why the others are wrong:

• A is likely sodium (Na), a reactive Group 1 metal, not a gas.
• B is likely chlorine (Cl), a reactive Group 7 halogen gas, not unreactive.
• C is likely oxygen (O), a reactive Group 6 gas essential for combustion, not unreactive.

Final answer: D