What defines a run-on sentence?

A run-on sentence is specifically characterized by containing two or more independent clauses that are improperly connected without the appropriate punctuation or conjunctions. In essence, independent clauses are complete thoughts that could stand alone as sentences; when they are joined incorrectly, it creates a run-on situation, which can confuse readers and detract from the clarity of the writing.

For example, a run-on sentence might look like this: "I went to the store I bought milk." Here, "I went to the store" and "I bought milk" are both independent clauses, yet they are not separated by a period or a conjunction.

The other options touch on related concepts but do not accurately define a run-on sentence. For instance, sentences that ask questions without punctuation do not pertain to the structural issues of run-on sentences. Similarly, sentences that are exceedingly long and complex may be grammatically correct but could still be clear and effective if properly punctuated. Lastly, sentences that contain incomplete thoughts or fragments indicate a different grammatical issue, known as sentence fragments, rather than the specific issue related to run-on sentences.