ment.getElementsByClassName('alink');
  var correctIndex = core.randi(0, linkElements.length);
  var correctText = linkElements[correctIndex].innerHTML;
  for(var i = 0, len = linkElements.length; i < len; i++) {
    var e = linkElements[i];
    if(e.innerHTML === correctText) {
      d3.select(e).on('click', function(){ link_state = 1.0; console.log(['click-link', link_state]); })
    } else {
      d3.select(e).on('click', function(){ link_state = -1.0; console.log(['click-link', link_state]); })
    }
  