As the water molecules re-freeze, what happens to the salt ions that are mixed in with the water?

Explanation:

Since salt is composed of two ions Na+ and Cl- it will attract to the opposite poles of the water and form a ion-dipole bond. This will cause the phenomenon freezing point depression where as the name states it will take a lower tempertature to freeze it. So instead of freezing at 0 degrees c it will freeze at a negative 2 or so on.

first one is the correct answer

it is the most commonly accepted one