in the event of having a number of questions unanswered with only a minute left that the child should fill in a 'guess' for each remaining answer and that instead of chosing randomly they should chose all a's or all b's etc
Sadly we did an experiment
DC you have one minute to answer ten questions, trial one all E and trial two random. You will be amazed and disappointed as the DC freezes trying to do random answers, even going back and amending them as they are not random enough.
Best bet is not to have questions left.