a solid, a liquid, and a gas (vapor) a solid and a liquid a solid and a gas (vapor) a solid only
I gave my students this multiple choice question: A hydrologist studies the location, movement, and quality of water. A hydrologist recognizes the importance that water exists as ___.

Only one answer is correct among these 4 choices:
- a solid, a liquid, and a gas (vapor)
- a solid and a liquid
- a solid and a gas (vapor)
- a solid only

Could you tell me which one is correct?

a solid, a liquid, and a gas (vapor)