The sequence of rock layers that best shows how the environment in an area changed over time would be one that reflects a progression of different ecosystems, indicating shifts in climate and geography.
Among the provided options, C (Forest → desert → ocean) demonstrates a clear sequence of environmental change, suggesting that the area originally had a forest, which transitioned to a desert, and then was submerged under ocean water. This progression indicates significant changes in the environment over time.
To summarize, the best response is:
C Forest → desert → ocean.