function buttonclick(answer,button,number)
{

   var right = "right"+number;
   var wrong = "wrong"+number;
   
   if (document.layers)
   {
      if (answer == button)
      {
         document.layers[right].className="respon";
         document.layers[wrong].className="respoff";
      }
      else
      {     
         document.layers[right].className="respoff";
         document.layers[wrong].className="respon";
      }
   }
   else  if (document.all)
   {
      if (answer == button)
      {
         document.all[right].className="respon";
         document.all[wrong].className="respoff";
      }
      else
      {
         document.all[right].className="respoff";
         document.all[wrong].className="respon";
      }
   }
   else
   {
      if (answer == button)
      {
         document.getElementById(right).className="respon";
         document.getElementById(wrong).className="respoff";
      }
      else
      {
         document.getElementById(right).className="respoff";
         document.getElementById(wrong).className="respon";
      }
   }

}