下面程序的运行结果是 #include＜iostream.h＞ class base{ protected: int a; public: base( ) {cout ＜ ＜ "0";} }; class base l: virtual base{ public: base l ( ) {cout ＜ ＜"1";} }; class base 2: virtual base{ public: base2 ( ) {cout ＜ ＜"2";} }; class derived: public base 1, public base2{ public:derived( ) {cout ＜ ＜ "3";} }; void main( ){ derive obj; cout ＜ ＜ endl;}A、0123 B、3120 C、0312 D、3012