单选题

以下代码的执行结果是？ public class Example { public static void main(String[] args) { Element[] a1 = new Element[1]; Element[][] a2 = new Element[2][1]; Element[][][] a3 = new Element[3][3][3]; System.out.print(a3[2][2][2]); a1[0] = new Element(); a2[0] = a2[1] = a1; a3[0] = a3[1] = a3[2] = a2; System.out.print(a3[2][2][2]); } } class Element { }

Question

A. 输出0

B. 输出null

C. 编译不能通过

D. 运行时输出异常