Although I don't get any JS errors I see the problem - it's the Limespired template messing things up.
Use this. I would also move it to the question help so it doesn't show in the alert that pops up if the question is unanswered. Note that this will only display the last option - gimme a minute to modify it to display the last two.
<script type="text/javascript" charset="utf-8">
$(document).ready(function(){
window.setTimeout(function() {
$('.survey-question-answer li:last').show();
$('.survey-question-answer input[type=hidden]:eq(0)').attr('value', 'on');
}, 50);
});
</script>
