7.B Antithesis

Antithesis works by building two halves out of matching parts, then swapping in opposite terms at each matching slot. 'Ask not what your country can do for you' sets up a frame: subject, verb, 'for you.' The second half has to fill that same frame and flip the one term that matters, 'for you' to 'for your country.' If the second half did anything else, the sentence would just stop; the whole point of the first half is to create a slot the second half must answer. That's why the sentence needs its second half to mean anything: the opposition is the argument, not a decoration on top of it.

The test for real antithesis is whether the two halves share a structure and trade opposed terms inside it. 'Many are called, but few are chosen' lines up called against chosen and many against few, each sitting in the same grammatical seat its partner occupies. A sentence like 'Many are called, but the process takes six weeks' has a 'but,' yet nothing in the second half answers 'many' or 'called'; it just adds information. 'But' signals contrast loosely; antithesis demands a matched frame where every slot gets answered.

Because the frame does the asserting, antithesis can make two things look opposed even when they aren't logically exclusive, as with 'we don't need more studies; we need a plan.' Studies and plans could coexist, but the matched structure forces them into a false either-or, and the argument then owes the reader proof that the opposition is real. This is why antithesis sits near parallelism and chiasmus: it borrows their matching shapes but adds the twist of opposite content, which is what makes the balance feel like proof rather than style.