应在下列程序划线处填入的正确语句是（ ）。class Base{ public: void fun(){ cout<<"Base class--fun\n"; }};class Derived:public Base{ public: void fun() { _____________ //显式调用基类的函数fun() cout<<"Derived class--fun\n"; }};
选项：

A:Base::fun();
B:this->fun();
C:Base.fun();
D:Base->fun();