The elements are the basic units that are indivisible and are defined by protons. The element Ar is classified as a noble gas in the periodic table. Thus, option A is correct.
Noble gas occupies the zero group in the periodic table and is unreactive and monoatomic gas that shares similar properties of being colorless, and odorless.
The gases helium, argon, neon, xenon, and krypton are noble gases that are inert, stable, and have low reaction rates that make them used in standard conditions.
The seven noble gases are unable to bond with the atoms of the other elements which makes them less reactive. Because of their less reactive nature, they are also called inert gases.
Therefore, argon (Ar) is a noble gas.
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