I’n pretty sure the answer is supposed to be about the tectonic plates. The plates constantly shift the land creating holes/dips in the earth and mountains in other places.
Hello!
I believe the best answer to your question would be Option C) excess carbon dioxide.
Hope this helps, and have a lovely rest of your day :)
The ocean acidification is generally caused by the vast amounts of carbon dioxide that humans release in the air gettting absorbed into the ground, causing the PH of the water to rise.
Hopefully this helps!