单项选择题

有如下程序： #include＜iostream＞ using namespace std; class Base1{ public: Base1(int D) {cout＜＜d;} ~Base1(){} }; class Base2{ public: Base2(int D) {cout＜＜d;} ~Base2 (){} }; class Derived:public Base1, Base2{ public: Derived(int a, int b, int c, int D) ; Base1(B) , Base2(A) , b1(D) , b2(C) {} Private: int b1; int b2; }; int main(){ Derived d(1, 2, 3, 4); return 0; } 运行时的输出结果是( )。