Choose the group of words that forms a complete sentence.

• A. Big, snarly animals in the cage.
• B. They're here—the small, the medium and the large.
• C. The last cow in the field?
• D. Again with the chicken!

Answer: (B)

A complete sentence expresses a full thought and needs both a subject and a finite verb. In this group, the subject is They and the verb is are, forming “They’re here.” The rest—the small, the medium and the large—adds detail without breaking the sentence, acting as a clarifying detail attached to the subject. That combination makes a full statement you can rely on in writing or speech. The other phrases don’t form complete sentences: one is just a noun phrase lacking a verb, another is a noun phrase that ends with a question mark, and the last is a fragment exclamation without a full verb and subject. So the one with a clear subject and finite verb that expresses a complete idea is the correct choice.