What human and natural changes affected the sea cow

This area was probably not the optimal habitat for the species. There is evidence that the sea cows were often injured or suffocated by ice floes and were not able to find enough food to stay healthy. This cold-water adapted species had in fact evolved from sirenian ancestors that had formerly occupied tropical warm waters along the California coast with its warm, shallow bays some 35 million years ago.

Well i had the same answer, so the correct answer would be a. but in this case it would be the one with plasma membrane and cell wall circled that is next to the hairy pill type of thing.