<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>

<script type="text/JavaScript">
<!--
function ValidateForm(form){

  var ErrorText;

  if ( form.elements['age'].selectedIndex == 0 ) 
  { 
    ErrorText = "Please select your Age.";
  }

  if (ErrorText) 
  {
    alert(ErrorText);
    return false;
  }

  return true;
}
-->
</script>

</script>
</head>

<body>

<form name="feedback" action="" method="post" onSubmit="return ValidateForm(this);">
  Your Age:
  <select name="age"> 
    <option value="">Please Select an Option:</option> 
    <option value="0-18 years">0-18 years</option> 
    <option value="18-30 years">18-30 years</option> 
    <option value="60+ years">60+ years</option> 
  </select>
  <input type="submit" name="SubmitButton" value="Submit">
  <input type="reset" value="Reset">
</form>

</body>
</html>