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()endl;
return 0;
A．5
B．7
C．9
D．12