【单选题】

若有以下程序：

#include ＜iostream＞
using namespace std;
classBase
public:
Base()
x=0;
int x;
;
classDerivedl: virtual publicBase
public:
Derivedl()
x=10;
;
classDerived2: virtual publicBase
public:
Derived2()
(
x=20;
;
classDerived: publicDerivedl,protectedDerived2 ;
int main()
Derived obj;
cout＜＜obj.x＜＜end1;
return 0;
该程序运行后的输出结果是
A．20
B．30
C．10
D．0