If you are drawn as a winner for the Megasack your entry still has to have the right answer to the question associated with it. Wrong answers don’t count in the draw.
The way it works, as you will see on the live broadcast on New Year’s Eve, is that first I pick a number between 1 and 16 using Random.org and that picks the day from which I then pick the Megasack winner, again using random.org. The winner is only the winner if they got the answer right for that day. The reason is that if we just picked from all entries then we’d be running a lottery and that needs a licence. However, you don’t need a licence for a ‘game of skill’. In this case the skill is in picking the right answer.
This explains why daytime TV programs run competitions with ridiculously easy questions to avoid having to declare themselves a lottery and get a licence for every competition they run.