单项选择题

下面程序的运行结果为
#include < iostream.h >
class A
static int n;
public:
A( )n=1;
A(int num) n = num;
void print( )cout<< n;

int A::n=2;
void main( )
A a,b (3);
a.print( );
b.print( );
cout<< end1;

A.11
B.13
C.23
D.33