有如下程序: #include<iostream> using namespace std class Point{ int x, y public: Point(int x1=0, int y1=0):x(x1), y(y1){} int get(){return x+y) } class Circle{ Point center int radius public: Circle(int CX, int cy, int r):center(cx, cy), radius(r){} int get(){return center. get()+radius} }; int main(){ circle c(3, 4, 5) cout<<c. get()<<end1 return (): } 运行时的输出结果是( )。 A) 5 B) 7 C) 9 D) 12