The answer is letter c. run-on sentences.
Run-on sentences are also called fused sentences. It has at least two parts, either one of which can stand by itself meaning; two independent clauses, but the two clauses have been smooshed together. Run-on sentences contain many ideas but they have no proper punctuation marks. Comma- splice on the other hand is different. It is composed of a run-on sentence or two independent clause connected only by comma. In Grammar, sentence fragment is just a part of a sentence, meaning it is a group of words which has no complete thought while subject complement is an adjective, noun or a pronoun or a predicative expression that follows a linking verb.