Use the rock key in the question to help you... Look at this image, what was happening in this areas past?

options:

the water level was shallow beach, then it rose to deep sea, then the water receded to a beach


water was deep and then kept getting shallower and shallower until there was no water in the area


the water level was shallow beach, then it rose to shallow sea, then the water receded to a beach


the area was covered by a shallow sea the whole time