Parallel structures are required for series and for most kinds of compounds. Within a sentence, a series is a sequence that consists of three or more words, phrases, or clauses. Compounds are formed when two parts of speech (or other grammatical units) are joined by a conjunctive word or words (and, or, either . . . or, etc.). In the following exercises, identify the sentence in which all the elements are parallel. If two options contain parallel structures, select the one that is most efficient (i.e., less repetitive).