In Challenge: Classification  oh noes guy says 

"Your javascript encountered a runtime error. Check your console for more information."

what do i have to do?

<script>
var answers = document.querySelectorAll('#answers li');
var rightAnswer = answers[0];
var wrongAnswer1 = answers[1];
var wrongAnswer2 = answers[2];
rightAnswer.className = "right-answer";
wrongAnsWer1.className = "wrong-answer";
worngAnswer2.className = "wrong-answer";
</script>