Which command is used to apply an undone action again?

Correct answer: Redo

Redo reapplies an editing action that was most recently reversed by Undo. For example, after typing a word, using Undo removes it; selecting Redo brings that typing back. Thus option C is correct. Save records the current document, Cut moves selected content to the clipboard, and Restore generally returns a file or system to an earlier state rather than repeating a reversed editing action.