What characterizes a complex sentence?

A complex sentence is characterized by having at least one independent clause and at least one dependent clause. The independent clause can stand alone as a complete thought, while the dependent clause cannot function independently and typically begins with a subordinating conjunction (like "because," "although," or "if").

This structure allows for the expression of more nuanced ideas, as the dependent clause can provide additional context or detail about the independent clause. For example, in the sentence, "Although it was raining, we decided to continue our picnic," "we decided to continue our picnic" is the independent clause, and "Although it was raining" is the dependent clause that adds more information to the main action.

The other options describe different aspects of sentence structure that do not fulfill the requirements of a complex sentence. An independent clause alone or a collection of dependent clauses does not create the complexity inherent to the definition of a complex sentence. Additionally, sentences with several independent clauses linked by conjunctions form compound sentences, not complex ones, highlighting the unique requirement for at least one dependent clause in a complex sentence.