multiple choice answers back to unselected mode

Not specifically, but you can set up this action without much difficulty. The standard question slide has a "correct" and an "incorrect" layer. If you set the slide to "reset to initial state" (slide properties) and then create a trigger to "go to current slide" upon some action - say, the timeline ending after 7 seconds or adding a button that says "try again" - you should get the result you want.