Which line of code can be used to replace the INSERT comment in order to output "hello"?

Which line of code can be used to replace the INSERT comment in order to output “hello”?
class C { public $ello = ‘ello’; public $c; public $m; function __construct($y) { $this->c = static
function($f) { // INSERT LINE OF CODE HERE }; $this->m = function() { return “h”; }; } } $x
= new C(“h”); $f = $x->c; echo $f($x->m);

A.
return $this->m() . “ello”;

B.
return $f() . “ello”;

C.
return “h”. $this->ello;

D.
return $y . “ello”;