b. the layer of oxide formed on statues made of metal
Explanation:
Chemical weathering is a process whereby rocks are disintegrated or weathered causing a chemical reaction thereby leading to change in the parent rock constituents .
In chemical weathering a new substance is usually formed after the weathering takes place.
From the question the layer of statue made by metal will likely form oxides of those metals. Example Silver will react with oxygen to form an entirely new substance like silver(i)oxide.
