Respuesta :
antithesis: a person or thing that is the direct opposite of someone or something else:
so the answer would be the use of “united” and “divided”
Antithesis is a rethorical device in which two opposite ideas are put together so as to achieve a contrasting effect, generally by introducing a parallel structure of the contrasted phrases.
In this case, an example of antithesis in this passage is the use of "united" and "divided," because the sentences introduced by these words share the same structure and express contrast.