单项选择题

有如下程序:
#include <iostream>
using namespace std;
class Point
public:
static int number;
public:
Point() number++;
~Point() number--;
;
int Point::number=0;
void main()
Point *ptr;
Point A,B;

Point* ptr_point=new Point[3];
ptr=ptr_point;

Point C;
cout<<Point::number<<endl;
delete []ptr;

运行时输出的结果是

A.3
B.4
C.6
D.7