What characterizes a complex sentence?

A complex sentence is characterized by having at least one independent clause and one subordinate clause. The independent clause expresses a complete thought and can stand alone as a sentence, while the subordinate clause adds additional information but cannot stand alone as a complete sentence. This combination allows complex sentences to convey detailed and nuanced ideas by linking related thoughts in a single sentence structure.

In contrast, other options describe different types of sentence structures. A sentence with two independent clauses would be considered a compound sentence, not complex. A sentence containing no clauses would not fit the definition of a complex sentence, and a sentence with three or more clauses could potentially be a compound-complex sentence but does not specifically define a complex sentence by itself. Thus, the defining feature of a complex sentence is the presence of both an independent and a subordinate clause.