Drag and Drop Issue - How to make objects that don't have a drop target turn "incorrect" if dropped somewhere

Thank you both very much! I can see it's working in the case you recorded (thanks for the recording by the way!)

BUT, I do have a Submit button in my case, and I need it because I can't tell learners if they are doing right/wrong as they move objects around, they need to complete their "selection" and than see if they were right. Now, let's say I drag the correct object into its drop target, and I don't touch the triangle and the square (which would be the correct solution for the exercise); what would happen to those two shapes as soon as I click submit? I think they would turn red because they are not in their correct drop target (the one outside the slide) and the exercise would be considered wrong. Or not?

I may be missing your point but I can't see how :)