Why Jesus Chooses 12 Disciples

There is this one saying that almost certainly Jesus said I think which is he is talking to the 12 disciples. When the kingdom comes U12 will be seated on 12 thrones ruling the 12 tribes of Israel. But why did Jesus choose 12 disciples in his book Jesus apocalyptic prophet of the new millennium Ehrman writes why did Jesus choosing 12 disciples. Why not nine or 15? The 12 disciples represent the true Israel the people of God who would enter into his glorious kingdom when the son of man arrives, says O'Connor.