In most of the world, the word "football" refers not to what Americans know by that name but to what Americans call "soccer."
In most of the world, the word "football" refers not to what Americans know by that name but also to what Americans call "soccer."
In most of the world, the word "football" refers not to what Americans know by that name but to what Americans call "soccer."
In most of the world, the word "football" refers not to what Americans know by that name but also to what Americans call "soccer."
The paired structure "not ... but" places two items in parallel; this structure frequently appears on the GMAT. The two pieces, each a single word, must come together: one without the other is incorrect, and variations (especially confusions with one piece of "not only ... but also") are not correct either.