In the following code, which class can be instantiated?
<code>
1 <?php
2 abstract class Graphics {
3 abstract function draw($im, $col);
4 }
5
6 abstract class Point1 extends Graphics {
7 public $x, $y;
8 function __construct($x, $y) {
9 $this->x = $x;
10 $this->y = $y;
11 }
12 function draw($im, $col) {
13 ImageSetPixel($im, $this->x, $this->y, $col);
14 }
15 }
16
17 class Point2 extends Point1 { }
18
19 abstract class Point3 extends Point2 { }
20 ?>
</code>

A.
Graphics

B.
Point1

C.
Point2

D.
Point3

E.
None, the code is invalid