Sedimentary rock layer B exists between two other layers of sedimentary rock, layers A and C. The ordering of layers A and C has not been altered since disposition, and the layers have not been overtu

Sedimentary rock layer B exists between two other layers of sedimentary rock, layers A and C. The ordering of layers A and C has not been altered since disposition, and the layers have not been overturned. Base on this information, what can be concluded with certainty?