Header php Get method from list

Header php Get method from list

In test.php I have the following code:
<php?
header ('Location: $link ');
$link = $_GET["id"]
ss1 = 'http://drrd.com';
ss2 = 'http://drrd2.com';
ss3 = 'http://drrd3.com';
ss4 = 'http://drrd4.com';
ss5 = 'http://drrd5.com';
ss6 = 'http://drrd6.com';
ss7 = 'http://drrd7.com';
?>
When I go to test.php?id=ss3 the page should redirect me to http://drrd3.com/
How could I do that?