function getObjRef(id) {
  if(document.getElementById) { return document.getElementById(id); }
  if(document.all) { return document.all[id]; }
}

/*

This works in Firefox, Netscape 6+, IE4+, Opera 7+, Konqueror 3, Safari, and 
IE5/Mac.

*/
function showQuestionsRel(selected) { //selected is the selected option
  var val = selected.value.toLowerCase(); //selected's value property is 
     // retrieved and converted to lower case for easier

  var el = getObjRef('optional'); //gets the object reference for the element

  if (val == 'n') { //if val is set to 'n' show the textbox

    el.style.display='block';

  } else {  //else hide it or keep it hidden.

    el.style.display='none';
  }
}