The item on the list with the lowest oxygen reactivity is -

Copper in the list is the least oxygen-reactive substance.

Any element's reactivity can be found by consulting the reactivity series.

All of the metals in this series are sorted from top to bottom in descending order. The metal in the highest position is the most reactive of all, whilst the metal in the lowest position is the least reactive.

Because zinc, Iron, and lead are on the top portion of the reactivity series, they will readily react with oxygen.