Mr. Frank says this line when they are all fighting.
He is saying that they don't need the Nazis to destroy them. They are destroying themselves by fighting. In this scene, they were fighting over food, which was certainly important -- however, Mr. Frank is saying that the good of all must be considered before individual needs.
Mr. Frank is saying that in order to survive, some sacrifice must be made, and the fighting must be stopped.
It might be said that Sergei´s reaction towards Yoni at his door might be option D. he might have been frightened because Yoni could discover the gold fish. so his reaction was kind of harsh, he did not what to answer the questions and he wanted the boy to go away from his house.
That he is dead and no longer with them
I think it might be D based on my searches
