有以下程序#include main(){ FILE *fp; int k,n,i,a[6]={1,2,3,4,5,6}; fp=fopen("d2.dat","w"); for(i=0;i<6;i++) fprintf(fp, "%d,",a[i]); fclose(fp); fp=fopen("d2.dat","r"); for(i=0;i<3;i++) fscanf(fp, "%d%d",&k,&n); fclose(fp); printf("%d,%d\n",k,n);}　　程序运行后的输出结果是_______。

A．1,2

B．3,4

C．5,6

D．123,456