Answer the following question given this paragraph: 

As the rust forms on the surface of the iron, it flakes off to expose more iron, which will continue to rust. Rust is clearly a substance that is different from iron. Rusting is an example of a chemical change. Some chemical changes are not as obvious but are still hugely important. For example, photosynthesis and cellular respiration are chemical changes that we could not live without. Chemical changes involve the combination, decomposition, or rearrangement of elements and compounds to form new substances.


Q: The combination decomposition or rearrangement of elements and compounds to form new substances is known as?

 Choices:

- ionic changes

- carbon changes

- mineral changes

- chemical changes

A:
chemical changes
