The image shows flat sedimentary rock layers in the foreground and angled sedimentary rock layers in the background. Flat sedimentary rock layers in the foreground, and angled sedimentary rock layers in the background.

According to the principle of original horizontality, what most likely happened to the rock layers in the background?

They cracked at an angle.
They were deposited at an angle.
They were deposited vertically and then shifted by a geologic event.
They were deposited horizontally and then shifted by a geologic event.