Which statement describes the law of superposition?

A Sedimentary rocks were originally in horizontal layers.

B In horizontal rock layers, each layer is younger than the one below it.

C Rock layers must be in existence before something can happen to them.

D Rocks that are not in horizontal layers were shifted by some geologic event.

The correct statement is B.

Explanation:

The law of superposition simply states that in an undisturbed sequence of sedimentary rocks, each layer is older than the one above and younger than the one below, that is, the strata are deposited on top of each other chronologically, where the oldest strata will be those located at the bottom and the younger at the top.

The answer is B, because the law of superposition states that the youngest rocks are on top, and the oldest are on the bottom.