In order to help the student expand his/her knowledge I will help answer the question. This in hope that the student will get a piece of knowledge that will help him/her through his/her homework or future tests.
The different rates of erosion are what a cave with several different depths most likely indicates. This is due to the fact that caves are formed by a combination of erosion, pressure and tectonic forces.
The correct choice is A. different rates of erosion
I hope it helps, Regards.