Using only uniformitarian calculations from the thickness of known sedimentary rocks, likely rates at which those rocks accumulated, and features in and under those sedimentary rocks, geologists working two to three hundred years ago estimated that the earth:

a) is less than about one-hundred-million years old.
b) s about one-hundred-million years old.
c) is more than about one-hundred-million years old.
d) is 4.6 billion years old.
e) has been here forever.

C) is more than about one-hundred-million years old.

Explanation:

The principle of uniformitarianism states that the present is the key to the past. The principle was popularized in the early 1800s . Scientist realized the earth was old - at least in the hundreds of millions of years.

The principle emanated from the fact that the thickness of sedimentary rocks found in the earth are product of sediments eradicated from the land and deposited on the sea. They studied notable features of sediments , the rate and pattern at which they accumulate.  

d is the logical answer but im not a 100% sure