Which sentence uses commas correctly? A. On August 18, 1920 Congress ratified the 19th Amendment to the United States Constitution. B. We will move our offices to San Francisco before September 30 2016, and open a new branch office in Boston by June 1 2020. C. Is Cairo Egypt, the city closest to the great pyramids? D. Please deliver the signed application to 1417 Corporate Boulevard, Baltimore, Maryland, by Monday, March 12.