Question

why can the geologic record be analyzed by looking at different rock layers?
all layers have the same age.
the layers have different ages with the oldest layers on top.
the layers have different ages with the youngest layers on bottom.
the layers have different ages with the youngest layers on top.

Explanation:

In geology, the principle of superposition states that in undisturbed sedimentary rock layers, the oldest layers are at the bottom and the youngest layers are on top. This allows geologists to analyze the geologic record by looking at different rock layers as each layer has a different age.

Answer:

The layers have different ages with the youngest layers on top.