Answer:
c) Fastest at the top
Step-by-step explanation:
The glacier is a large mass of ice, moving slowly down a slope as a compact unit. While in general it can be said that the whole glacier moves as one, not all parts of it move with the same speed. The bottom part of the glacier is moving the slowest, which is a result of the friction between the ice and rocks at the valley and walls. The central part tends to move slightly faster as it is avoiding the friction with the rocks, while the top part tends to be the fastest as it has the least pressure on it, so its movement is the easiest.