单项选择题

有以下程序
#include <stdio.h>
main( )
FILE *fp;int i,a[6]=1,2,3,4,5,6;
fp=fopen("d3.dat","w+b");
fwrite(a,sizeof(int),6,fp);
fseek(fp,sizeof(int)*3,SEEK_SET);/*该语句使读文件的位置指针从文件头向后移动3个int型数据*/
fread(a,sizeof(int),3,fp);fclose(fp);
for(i=0;i<6;i++)printf("%d,",a[i]);

程序运行后的输出结果是

A)4,5,6,4,5,6,
B)1,2,3,4,5,6,
C)4,5,6,1,2,3,
D)6,5,4,3,2,1,