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