The subordinate clause is "unprotected animals got swept out" and the main clause is because "when waves rush in". hope u get it right ;)
I believe the answer is A., though it's been a while since I read the story.
Although there is not a current paragraph related here. According to the actual meaning of the word, vicissitudes, it is possible to say taht this word means difficulties (mainly related to difficult times), that are going to have possitive consequences. In other words, it is possible to say that it has a possitive and a negative meaning at the same time.
From the options given, the statement that best explains the given phrase is this: WEALTH MAKES PEOPLE VIRTUOUS. The reference made to the inability of an empty sack to stand upright also lends to this, because when a sack is filled up, it becomes easy for it to stand upright. That is to say, may a man has wealth, it's easy to be virtuous.
