At a Historic Civil War Battleground, a Stack of Cannonballs

At a historic Civil War battleground, a stack of cannonballs looked like the picture below on the far left.Removing the top cannonball resulted in the middle view, and removing the next layer resulted in the view on the right.What sort of packing was used in stacking the cannonballs?

A) simple closest-packed
B) hexagonal closest-packed
C) cubic closest-packed
D) random packed
E) body-centered closest-packed