What distinguishes a run-on sentence?

A run-on sentence is characterized by the incorrect joining of two independent clauses without proper punctuation or a conjunction. An independent clause contains a subject and a verb and expresses a complete thought. For example, the sentence "I love to read I have many books" is a run-on because it merges two complete thoughts without a proper conjunction or punctuation such as a semicolon or a period.

In contrast, the other options present features that do not define a run-on sentence. A run-on doesn't need to lack clauses, contain a conjunction, or be limited to one independent clause; it specifically involves the improper combination of two or more independent clauses that can stand alone as distinct sentences.