Answer:
A. Uniformitarianism
Step-by-step explanation:
The principle of Uniformitarianism was proposed by a Scottish Geologist, James Hutton.
The principle is simply stated as "the present is the key to the past".
The processes that have occurred in geologic past is still in play today. By looking at rock sequences in our present day, we can actually have a firm grasp of the processes they have undergone in the past.