Final answer:
Santiago gets up from the sand and begins to laugh for appreciation of life's irony.
Step-by-step explanation:
After the attackers leave, Santiago gets up from the sand and begins to laugh for appreciation of life's irony.
In the given passage, Santiago reflects on the idea that drowning would be a comfortable arrangement, a cessation of hostilities accompanied by relief.
This reflection shows that Santiago has gained a new perspective on life and finds humor in the irony of his temporary agony turning into relief. Therefore, option C) Appreciation of life's irony is the correct answer.