Answer:
A chemical reaction.
Step-by-step explanation:
A chemical reaction can be defined as a chemical process which typically involves the transformation or rearrangement of the atomic, ionic or molecular structure of an element through the breakdown and formation of chemical bonds to produce a new compound or substance.
Since the Statue of Liberty is made out of copper and was once shiny and copper colored. Over the years, the copper has gone through a process called oxidation, where it has changed into a new material. Thus, this is a chemical reaction.