new molecules are formed. the mass of the sample is increased. the arrangement of the molecules changes. energy is absorbed by the molecules.
I gave my students this multiple choice question: As a sample of water turns to ice,

Only one answer is correct among these 4 choices:
- new molecules are formed.
- the mass of the sample is increased.
- the arrangement of the molecules changes.
- energy is absorbed by the molecules.

Could you tell me which one is correct?

the arrangement of the molecules changes.