Correlative conjunctions must always...

Correlative conjunctions, such as "either...or," "neither...nor," and "both...and," are pairs of conjunctions that work together to join words, phrases, or clauses that are of equal grammatical importance. For example, in the phrase "both the teacher and the student," both elements are equally significant, and the conjunctions are used together to connect them effectively.

The correct answer highlights that correlative conjunctions must appear together in the same sentence to fulfill their function of linking related items. When they are used, the two conjunctions must be placed adjacent to each other, which ensures clarity and maintains parallel structure within the sentence. This joint appearance is crucial for the grammatical correctness and coherence of the sentence.

In contrast, correlative conjunctions do not need to be used individually nor connect items of unequal rank, and they certainly do not require the beginning of a new paragraph, which would disrupt the flow and clarity intended by their use. The proper functioning of correlative conjunctions hinges on their paired usage within a single sentence structure.