单选题

class Alpha { public void foo()...

Question

class Alpha {
 public void foo() { System.out.print("Afoo ") }
 }
 public class Beta extends Alpha {15. public void foo() { System.out.print("Bfoo ") }
 public static void main(String[] args) {
 Alpha a = new Beta()
 Beta b = (Beta)a
 a.foo()
 b.foo()
 }
 }

以上代码的执行结果是(  )

A. Afoo Afoo

B. Afoo Bfoo

C. Bfoo Afoo

D. Bfoo Bfoo