The correct answer is:
B. It was an ocean boundary where federal agents had no power to make arrests
William S. McCoy is credited with the idea of bringing large boats just to the edge of the three-mile limit of U.S. jurisdiction, and there selling rum to contact boats, local seamen, small boats, floatplanes, and flying boats. Soon the three-mile limit became known as "Rum Line" and the ships waiting were called "Rum Row".