An engineer pours hot, liquid metal into a mold. As it cools, it takes the form of a solid beam.
In the process described above, what is the evidence that a physical change occurred?
I. The liquid metal cooled to form a solid.
II. The shape of the metal changed.
III. The metal changed into new substances.
 A. 
I and II only
 B. 
III only
 C. 
II only