An option between right and wrong answer

Hi all !

I would like to have a third option in questions between Right Answer and Wrong Answer. A sort of "I don't know" answer that would skip the question and add 0 points to the result while a correct answer would score 2 points and a wrong one would be -1.

I tried to add a simple "IDK" button that would skip to the next question. And it works just fine ONLY if the student didn't click any answer before deciding they don't know the right answer and prefer to not lose any points. In this case the score points don't change. But if an answer is selected or an item is dropped in a dropzone, the IDK button acts as a validation button for the question. It doesn't show if I display the Results.ScorePoints variable in the slide, but the answer is definitely taken into account on the result slide.
I can work around this by reinitialising every answer to its default state in a multiple choice quiz by trigger before the "go to next slide" trigger. It's a little bothersome to do, but it works. However I don't know how to work around the problem in a drag-and-drop question.

Is there an easier way to add an IDK option in quizzes that would add no points ?

Thanks !