An example would be a version of the trolley problem where you can either allow the track to remain on its current path which is empty, or divert it to harm an individual unnecessarily. This is a choice between a universally good outcome or a universally bad outcome.
Whereas the typical trolley problem is an ethical dilemma since both options are harmful and neither are ideal so it’s choosing between 2 bad outcomes.
Moral/ethical imperative.
That describes whichever of the 2 options is morally correct more than the situation in which there is a clear correct option, doesn’t it?