What does the principle of uniformitarianism state?

B. Sedimentary rocks are deposited in approximately horizontal layers; if they are not horizontal, they have been rearranged by the action of forces within the Earth.

C. Younger rocks are deposited on top of older rocks in undisturbed sedimentary rock laters.

D. Specific groups of organisms have followed, or succeeded, one another in a definite sequence through Earth's history.

Answer:

The principle of Uniformitarianism state Geologic processes taking place on the Earth today operated similarly in the past and can be used to explain past geologic events.

Explanation:

Uniformitarianism is a geological doctrine, explains the present geologic process occurs at the same rate which was observed today in the same method for all the earth geological features.
The Doctrine of Uniformity is the other name for Uniformitarianism. The concept in the Uniformitarianism is the present is "the key to the past". There are many concepts in geoscience but it is considered an important one.
It was developed in the late 1700s. It says that the landforms that present on the earth's surface are not based on a catastrophic process.