单项选择题

如下程序的输出结果是
#include<iostream>
using namespace std;
class A
public:
A( )cout<<"A";

class Bpublic:B( )cout<<"B";;
class C:public A
B b;
public:
C( )cout<<"C";

int main( )C obj;return 0;

A.CBA
B.BAC
C.ACB
D.ABC