有如下程序:#include <iostream>using namespace std;class Base { public: void fun() {cout<<"Base:: fun"<<end1; }};class Derived: public Base ( public: void fun() { ____________________________ cout<<"Derived:: fun"<<end1; }};int main() { Derived d;D. fun();return O;}已知其执行后的输出结果为:Base:: funDerived:: fun则程序中下划线处应填入的语句是( )。
A.Bas fun ();
B.Base:: fun ();
C.Base->fun();
D.fun()