The paragraph that reflects a sighful moment is "Instead, I would sit by myself under a big pine tree in the courtyard, watching the other kids laugh and joke with their cliques at lunch." but she was too shy to join them. The climax is reflected in "For me, it wasn't until eighth grade that I found out how courageous I could be."
C is most likely the correct answer.
Organizing sentences around a central idea creates a paragraph.
I believe it is B isn't, because if you use the others it most likely sounds like slang.