进入某个行业的难易程度通常受到下列因素影响（）。

A.社会需求

B.规模经济

C.产品差别

D.在位优势

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

A．12

B．14

C．1234

D．123456