Concept:Saving an existing document under a new name is done using the “Save As” command.Explanation:A new file is first saved using the “Save” command.To keep the old file and create another copy under a different name, the user chooses “Save As”.“New” creates a blank document, while “Rename” changes a file name but is not the usual command inside a document for saving a copy.Therefore, the correct option is “Save As”.Answer:D. save as