I initially thought the same as Tim - to stop reporting the quiz as needing attention when attempts are no longer possible (B) - but having read Fred's latest post, I now think that the best solution would be to stop reporting when there is at least one finished attempt (C). The quiz has been done, and the student shouldn't need reminding that further attempts are possible. It's also a simple, easy-to-understand solution. Solution (B) might worry certain students - 'I've done the quiz so why am I still being reminded of it? Is there something I have forgotten?'
Stephen's suggestion of reporting various scenarios would be great as a separate (improvement) issue.