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.
I believe that Napoleon did it because we wanted to kick out snowball for complete power. Napoleon wanted to get snowball out and he used squealer to lie to the other animals. Just to have them go against snowball.