Final answer:
To duplicate an object on a slide, you can use Ctrl + D, which is a shortcut for duplicating. Ctrl + C and Ctrl + V are for copying and pasting respectively, while Ctrl + X is for cutting.
Step-by-step explanation:
To make a copy of an object on a slide, the command you would use is Ctrl + D. This command duplicates the selected object, allowing you to place the copy elsewhere on the slide. Alternatively, you could use Ctrl + C to copy the object and then Ctrl + V to paste it, but Ctrl + D is a quicker method as it combines both actions into one shortcut.