Which of the following describes a compound-complex sentence?

A compound-complex sentence is characterized by the combination of multiple independent clauses and at least one dependent clause. This structure allows for more complex ideas and relationships to be expressed in a single sentence, enhancing the richness of the writing.

In a compound-complex sentence, the independent clauses can stand alone as complete sentences, while the dependent clause cannot stand alone and provides additional information. For example, "Although it was raining, I went for a run, and my dog joined me." In this case, "I went for a run" and "my dog joined me" are independent clauses, and "Although it was raining" is the dependent clause, creating a compound-complex sentence.

The other answer choices do not fit this definition, as they describe simpler structures, such as a single independent clause or combinations that do not include both elements necessary for a compound-complex sentence. Therefore, the correct answer effectively captures the necessary components of this type of sentence structure.