Which is an application of the principle of uniformitarianism?

A.

ordering a group of fossils from largest to smallest

B.

examining a rock to find out what minerals are in the rock

C.

studying a modern river valley to learn about how ancient rock layers formed

D.

counting tree rings to determine the age of a tree

"Studying a modern river valley to learn about how ancient rock layers formed" is the one among the following choices given in the question that is an application of the principle of uniformitarianism. The correct option among all the options that are given in the question is the third option or option "C".