There is a third option, spoil your ballot. It's invalid then, yes, but it's a statistic that the election/party analysts will track. Up to a certain threshold

There is a third option, spoil your ballot. It's invalid then, yes, but it's a statistic that the election/party analysts will track. Up to a certain threshold a spoiled ballot might be considered a mistake, but once over that threshold, it could me something more. For instance, that voters are not interested by the policies of any parties on the ballot.