<script type="text/javascript">
function change()
{
var select = document.getElementById('select');
var option1 = document.getElementById('select1');
var option2 = document.getElementById('select2');


   switch (select.value)
   {
      case "1":
	  option1.style.display='block';
	  option2.style.display='none';
	  option3.style.display='none';
	  break;
	  case "2":
	  option1.style.display='none';
	  option2.style.display='block';
	  option3.style.display='none';
	  break;
     
   }
}
</script>