单选题：如下程序的运行结果为：（ ）。

如下程序的运行结果为：（ ）。 @[D](2)
```
interface A {
}

class C {
}

class B extends D implements A {
}

public class Test {
public static void main(String[] args) {
B b = new B();
if (b instanceof A)
System.out.println("b is an instance of A");
if (b instanceof C)
System.out.println("b is an instance of C");
}
}

class D extends C {
}

```
A. 没有输出
B. b is an instance of A.
C. b is an instance of C.
D. 输出b is an instance of A，然后是b is an instance of C.




A.没有输出
B.b is an instance of A.
C.b is an instance of C.
D.输出b is an instance of A，然后是b is an instance of C.


答案：D