If you don't mind me asking, what are the following?
Questions like this are difficult to answer without more context, although there are some clues about the symbolism in this brief excerpt. You can read the whole short story here: http://images.pcmac.org/SiSFiles/Schools/AL/MobileCounty/TheodoreHigh/Uploads/Forms/Reading_Packet_with_Text_-_The_Rockpile_by_James_Baldwin_-_20150323.pdf
In the story, boys are always getting hurt. Some boys are afraid to play there because it is dangerous. The provided passage also talks about fighting and danger. If this were my assignment, I would choose C) It shows its dangers.
In this story, "My sister's keeper", the main character Anna, is the keeper because she must donate organs and blood to her sister to keep her alive.