The sentence that uses commas correctly is: "Robert lives in Columbus, Georgia, and his sister lives in Columbus, Ohio."Commas are used in a sentence to separate two or more items, phrases or clauses in a sentence. In this case, the sentence is separating two locations, so it is important to use commas in the correct way to make the meaning clear.The first option does not use a comma between Columbus and Georgia, so it can cause confusion as to whether Columbus Georgia is a single location. The third option uses a comma after "sister," which is not needed since there are only two people mentioned. The fourth option uses a comma after "lives," which is not needed either and can cause confusion.