The image below shows a stack of rock layers exposed in a cliffside. These layers have a fault running through them. A fault is a crack along which rocks move. When these layers first formed long ago, there was no fault present. At some time later, tectonic forces cracked the layers, forming the fault. Then, the rocks on either side of the fault moved. Using the layer marked a as a guide, determine how the rocks moved along the fault.
A.
The rocks on both sides of the fault moved down the same distance.
B.
The rocks on the left side moved up, and the rocks on the right side moved down.
C.
The rocks on the right side moved up, and the rocks on the left side moved down.
D.
The rocks on both sides of the fault moved up the same distance.