Freezing means changing from a liquid into a solid by reducing heat energy.
Solid ice is melted into liquid water.
Reducing heat energy turns water into ice. .
How does water turn to ice?

[a] Adding air
[b] The bending of a ray of light
[c] Warm air moving into cold air
[d] Increasing heat energy
[e] It used to be covered by water
[f] evaporation
[g] Adding salt
[h] Reducing heat energy