请选出以下程序的输出结果 class A { public void func1() { System.out.println("A func1 is calling"); } public void func2() { func1(); } } class B extends A { public void func1() { System.out.println("B func1 is calling"); } public void func3() { System.out.println("B func3 is calling"); } } class C { public static void main(String[] args) { A a = new B(); a.func1(); a.func2(); a.func3(); } }