rea');
  div.html(''); // clear previous problem, if any
  var correctText = createLinks(div);

  var any = core.getOpt(core.QueryString, 'any', false); // click Any link?

  var link_state = -1.0
  var elements = document.getElementsByClassName('alink');
  var correctIndex = core.randi(0, elements.length);
  var correctText = elements[correctIndex].innerHTML;
  for(var i = 0, len = elements.length; i < len; i++) {
    var e = elements[i];
    if(e.innerHTML === correctText) {
      d3.select(e).on('click',