It dissolves the rocks by pooling on surfaces. It breaks the rocks by expanding in openings. It smooths the rocks by colliding with them. It moves the rocks by pressing on them.
I gave my students this multiple choice question: How does ice change the shape of rocks?

Only one answer is correct among these 4 choices:
- It dissolves the rocks by pooling on surfaces.
- It breaks the rocks by expanding in openings.
- It smooths the rocks by colliding with them.
- It moves the rocks by pressing on them.

Could you tell me which one is correct?

It breaks the rocks by expanding in openings.