Miss Manners: How do I refuse alcohol to guests who will be driving home?

A host is seeking advice from Miss Manners regarding the proper way to graciously refuse alcohol to dinner guests who will be driving home. Although the guests may specifically request alcoholic beverages, the host prefers not to serve any alcohol to a designated driver. The inquiry focuses on maintaining politeness while ensuring safety, emphasizing that the host's preference is not based on the guests' habits but on the responsibility of driving.