Final answer:
The freezer lowers the temperature of the water below its freezing point, causing the water molecules to slow down and form a solid structure called ice.
Step-by-step explanation:
When liquid water is frozen in a freezer, the freezer lowers the temperature of the water below its freezing point, which is 0°C (32°F). This causes the water molecules to slow down and come together, forming a solid structure known as ice. So, the freezer causes the change in the water by reducing its temperature and creating the conditions for freezing to occur.