In the given illustration, it is observed that at first molecules are dispersed without any type of configuration or order and they adapt to the container shape. It means that they represent a liquid.
At the second stage, molecules are ordered and they have a defined shape, which is characteristic of solids.
It means that the change converted a liquid into a solid.
This is known as freezing. A liquid is frozen to became a solid, one example is water and ice.
It means that the correct answer is Freezing.
During freezing you release energy, this is because the liquid has to lose heat to become a solid. The answer to the second part is releases.