Question

how does the principle of crosscutting relationships help a geologist determine the relative ages of rock?
a fault in a layer is younger than the layer it affects.
rocks included in a layer are older than the surrounding layer.
younger rock is deposited on top of older rock.
all rock is originally deposited in flat layers.

Explanation:

The principle of cross - cutting relationships states that a fault or intrusion is younger than the rocks it cuts through. So, a fault in a layer is younger than the layer it affects.

Answer:

A. A fault in a layer is younger than the layer it affects.