Answer the following question given this paragraph: 

Metal exposed to the outside elements will usually corrode if not protected. The corrosion process is a series of redox reactions involving the metal of the sculpture. In some situations, the metals are deliberately left unprotected so that the surface will undergo changes that may enhance the esthetic value of the work.


Q: What process typically occurs to metal exposed to outside elements?

 Choices:

- shrinkage

- extraction

- explosion

- corrosion

A:
corrosion
