What is the main characteristic of a compound sentence?

A compound sentence is defined by the presence of two or more independent clauses that are joined together. Independent clauses are complete thoughts that can stand alone as sentences, and they are typically connected using a coordinating conjunction (such as "and," "but," or "or") or a semicolon. This structure allows the sentence to convey multiple related ideas with clarity.

The other options do not accurately represent the nature of a compound sentence. For instance, a sentence containing a single independent clause does not meet the criteria of being compound, as it lacks the necessary multiple clauses. The mention of a main idea at the end relates more to sentence focus or structure rather than the definition of a compound sentence. Similarly, a list of details may appear in various types of sentences, but it does not reflect the characteristic of having multiple independent clauses. Thus, the defining feature of a compound sentence is indeed the combination of two or more independent clauses.