Which keyword should be used in the line marked with "KEYWORD" instead of "self"

Consider the following code. Which keyword should be used in the line marked with
“KEYWORD” instead of “self” to make this code work as intended? abstract class Base {
protected function __construct() { } public static function create() { return new self(); //
KEYWORD } abstract function action(); } class Item extends Base { public function action() {
echo __CLASS__; } } $item = Item::create(); $item->action(); // outputs “Item”

A.
static