The answer should be option B. the destructive nature of life
The shovel-nosed sharks are little more than moving appetites that thoughtlessly and gracelessly attack the marlin. As opponents of the old man, they stand in bold contrast to the marlin, which is worthy of Santiago's effort and strength. They symbolize and embody the destructive laws of the universe and attest to the fact that those laws can be transcended only when equals fight to the death.
I think you will be helpful.
