40）有以下程序 #include main() { FILE *fp; int i=20,j=30,k,n; fp=fopen("d1.dat","w"); fprintf(fp,"%d\n",i);fprintf(fp,"%d\n",j); fclose(fp); fp=fopen("d1.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)20 30 (B)20 50 (C)30 50 (D)30 20