In a Plastically Flowing Alpine Glacier, The

In a plastically flowing alpine glacier, the:

A) center flows slower than the sides, but the center layers move faster than the deepest layers.
B) center, sides, and deeper layers all move at the same speed.
C) center flows faster than the sides, and the center layers move faster than the deepest layers.
D) center flows faster than the sides, but the center layers move slower than the deepest layers.