Which one of the following metals does not react with oxygen, water or

Which one of the following metals does not react with oxygen, water or acids?

Na
Cu
Fe
Au
This question was previously asked in
UPSC CAPF – 2021
Metals vary widely in their chemical reactivity. Some are highly reactive, readily reacting with oxygen, water, and acids, while others are much less reactive, sometimes referred to as noble metals.
Sodium (Na) is an alkali metal and is extremely reactive, reacting vigorously with oxygen, water, and acids. Copper (Cu) is moderately reactive; it reacts with oxygen to form oxides and with certain acids (like nitric acid or hot sulfuric acid) but is relatively stable in air and water compared to alkali metals. Iron (Fe) is also reactive; it rusts in moist air (reacts with oxygen and water) and reacts with acids. Gold (Au) is a noble metal, known for its low reactivity. It resists reaction with oxygen at normal temperatures, water, and most acids. It can only be dissolved by highly corrosive mixtures like aqua regia (a mixture of nitric acid and hydrochloric acid).
The reactivity series of metals ranks metals according to their reactivity. Gold is very low in the reactivity series, indicating its low tendency to participate in chemical reactions.