<?php
$query=mysqli_query($con,"select * from reg where user_id = '".$_GET['id']."' ");
$row=mysqli_fetch_array($query);
?>
<select name="sex" id="opt2">
<option value="">select</option>
<option value="Male" selected="selected">Male</option>
<option value="Female" selected="selected">Female</option>
</select>