"a is a testable explanation that can be verified or falsified."

Hypothesis is the answer.

c . slower and started moving in place.

Explanation:

Matter can exist generally in three phases, as a solid, liquid or gas. But it can be transformed from one phase to another by the removal or application of heat energy.

The water was initially in a liquid form in the sealed tank until energy was transferred out of the substance. Thus, this causes a change of state in which the water turns to a solid. Whereby during the process, the molecules of the water moved slowly until they are fixed at a point, and vibrates individually at their individual point.

Therefore the molecules of water moved slower and stated moving in place (i.e vibrating at a point). The water turns to an ice.