A scientist found a stack of rock layers which contained many kinds of fossils. A few kilometers away from this stack, the scientist found a nearly identical stack of layers which contained the same combination of fossils.
Which of the following is probably true of the stacks and the fossils they contain?
A. They represent the same time interval of Earth's history.
B. They represent similar environmental conditions in Earth's past.
C. They represent similar life conditions in Earth's past.
D. all of these