Which choice can be a solid, liquid, or a gas?

A. steel

B. silver

C. water

D. carbon dioxide

I believe that your option C would be the correct answer. We know that water can turn to a solid materail because during cold temperatures, water turns to ice.

We know that water can turn to gas, as water can evaporate.

And also, we know that water is obviosly a liquid.

Therefore, Option C would be your answer.