Which unit is defined as the largest purely grammatical unit in a language?

• A. sentence
• B. clause
• C. phrase
• D. utterance

Answer: (A)

In grammar, the largest unit that remains purely grammatical is the sentence. A sentence expresses a complete thought and is built from a syntactic structure that can include a subject and a predicate, and it can stand alone. A clause is smaller because it’s a single group with a subject and predicate, and it may not express a complete thought on its own if it’s dependent. A phrase is even smaller, lacking either a subject or a predicate, so it can’t convey a full proposition by itself. An utterance refers to actual speech or writing as it’s used in context, which brings in discourse and pragmatic features beyond grammar. Since the question emphasizes a purely grammatical unit, the sentence is the best fit because it is the largest unit governed by grammatical rules.