若有以下程序: #include <iostream> using namespaces std; class A public: A () A (int i) x1=i; void dispa() cout<< xl= <<xl<< , ; private: int x1; ; class B : public A public: B () B (int i):A(i+10) x2=i; void dispb() dispa (); cout << x2= <<x2<<end1; private: int x2; ; int main () B b(2); b.dispb (): return 0; 程序运行后的输出结果是( )。
A.x1=10,x2=2
B.x1=12,x2=10
C.x1=12,x2=2
D.x1=2,x2=2