Which is true about a dependent clause?

A dependent clause is a group of words that includes a subject and a verb but does not express a complete thought, which is why it cannot stand alone as a sentence. This is a key characteristic that distinguishes it from an independent clause, which can function as a complete sentence because it conveys a full idea. For example, in the clause "because I was tired," there is a subject ("I") and a verb ("was"), but it leaves the reader hanging, not providing a complete thought. Thus, it relies on an independent clause to make sense and convey a full message.

Regarding the other options, a dependent clause does not express a complete thought (which is a defining feature), and it does not start exclusively with a pronoun—dependent clauses can start with subordinating conjunctions, such as "because," "although," or "if." Also, since it cannot stand alone, any mention of it being able to function as a complete sentence or to exclusively begin with a pronoun is inaccurate.