Scientists are examining different sea floor structures like those in the model of the Earth's crust below.


The distance between X and Y represents thousands of kilometers of distance on Earth. The scientists notice that the rocks located at point X are older than the rocks located at point Y. What does this information about the age of the rocks indicate to the scientists?
A.
There is an underwater volcano producing new rock at point X.
B.
The sea floor is moving from Y to X over the course of millions of years.
C.
New rock is constantly covering old rock on the ocean floor.
D.
The sea floor is moving from X to Y over the course of millions of years.