单项选择题

有下列程序:
#include<stdio.h>
void main()

FILE *fp;int a[10]=1,2,3,i,n;
fp=open("d1.dat","w");
for(i=0;i<3;i++)fprintf(fp,"%d",a[i]);
fprintf(fp,"\n");
close(fp);
fp=open("d1.dat","r")
fscanf(fp,"%d",&n);
fclose(fp);
printf("%d\n",n);

程序的运行结果是( )。

A.12300
B.123
C.1
D.321