Answer:
B
Step-by-step explanation:
Rivers flow to the ocean because most water forms connect, the exceptions are bodies of water like lakes and bays, so it can't be A. Animals in a river are always moving and by the animals moving to the ocean it won't threaten the ocean. Just because people dump waste in a river doesn't mean that they will dump it in the ocean, that is just an inference, so its not d.
Most bodies of water are connected so the rivers will carry the waste into the ocean so the answer is B