What is a sentence fragment?

A sentence fragment occurs when a phrase does not present a complete thought and is missing an essential component, typically either a subject or a predicate, or it may be a subordinate clause that cannot stand alone. The essence of a sentence fragment is its inability to convey a full idea, which leaves the reader expecting more information or context.

In contrast, a complete sentence would have both a subject and a predicate, fully expressing a thought. The other options describe characteristics of sentences or clauses that do not accurately define a sentence fragment. For instance, independent clauses can stand alone as complete thoughts, and a sentence with multiple subjects could still be complete if it includes a predicate. Thus, the definition of a sentence fragment centers on its lack of completeness, which option B encapsulates effectively.