What are the written signs referred to in John 20:31? John 20:30-31

30 And many other signs truly did Jesus in the presence of his disciples, which are not written in this book:
31 But these are written, that ye might believe that Jesus is the Christ, the Son of God; and that believing ye might have life through his name.

My question is about verse 31, what are the signs which are written? Is it A) what Jesus does in chapter 21, B) what he has done during his life (as recorded by John), or C) is it something else?
If it is A, would this be an example of where a chapter breaks up the record (chapters are arbitrary)?
If it is C, what are the signs and where does John reference them?
It refers to the entire book, but especially the Book of Signs, John 1:19 - 12:50. (As with your note about arbitrary chapter beaks, notice that this doesn't align with the beginning of a chapter.) There are seven miracles or signs that John uses to establish Christ as the Son of God 


Wedding at Cana
Healing the official's son
Healing the paralytic
Feeding the 5000
Walking on water
Healing the blind man
Raising Lazarus


Some add the Crucifixion, Resurrection, and/or the miraculous catch of fish. However, the list of seven is fairly common, a nice biblical number, and has some interesting theology developed from it.