Use the diagram below to answer the question. If ammonite fossils are dated to be approximately 65 million years old which of the following is true according to this fossil record?

A Rock layer D is relatively younger than 65 million years old.
B Rock layer B is relatively younger than 65 million years old.
C Rock layer C is relatively younger than 65 million years old.
D Rock layer A is relatively younger than 65 million years old.