changes in state. states of matter. properties of matter. changes in properties.
I gave my students this multiple choice question: Gases can be easily compressed and are able to expand to fill their containers. These descriptions of gases are examples of

Only one answer is correct among these 4 choices:
- changes in state.
- states of matter.
- properties of matter.
- changes in properties.

Could you tell me which one is correct?

properties of matter.