solids only. liquids only. gas, liquids, and solids. gas and a vacuum only.
I gave my students this multiple choice question: A longitudinal wave, such as a sound wave, can travel through

Only one answer is correct among these 4 choices:
- solids only.
- liquids only.
- gas, liquids, and solids.
- gas and a vacuum only.

Could you tell me which one is correct?

gas, liquids, and solids.