若有以下程序: #include <iostream> using namespace std; class Base { public:Base(){ x=0;}int x; }; class Derivedl : virtual public Base { public:Derivedl(){ x=10;} }; class Derived2 : virtual public Base { public:Derived2(){ x=20;} }; class Derived : public Derivedl,protected Derived2 { }; int main () {Derived obj;cout<<obj.x<<end1;return 0; } 该程序运行后的输出结果是( )。
A.10
B.20
C.30
D.0