Respuesta :
Sentence four. It is a fragment because it cuts off and sounds incomplete.
Answer: D) Sentence 4.
Explanation: a sentence fragment is a group of words that form a dependent clause (it doesn't make sense on its own), in order to be a complete sentence, it has to be at least one independent clause (a phrase that has a subject, a verb and has meaning on its own). From the given options, the phrase "while I waited for the bell to ring" is a dependent clause, so this means that it is a fragment and not a complete sentence.