When exposed to very high temperatures, metals like iron can be turned into fluids that flow and can be poured into molds. What happens within the iron to allow it to flow? A
The structural energy of the solid decreases, and the particles begin to collide with high frequency.

B
The structural energy of the solid increases, and the particles begin to slide past each other.

C
The particles collide at an increasing rate until reaching equilibrium structural energy.

D
The particles vibrate about equilibrium in an effort to minimize structural energy.