Answer : Loud noises disturbed the neighbors.
The only complete sentence from the choices above is the sentence in letter B, "Loud noises disturbed the neighbors". A sentence can be called a complete sentence if it begins with a capital letter and ends with punctuation marks such as period, exclamation point or question mark. Most importantly, a complete sentence must be made up of a main clause with a subject and verb that expresses a complete thought. In the sentence in letter B, the subject is "loud noises" while the verb is "disturbed", and it does express a complete thought.