有以下程序#include main(){ FILE *fp;int i, a[6]={1,2,3,4,5,6}, k;fp = fopen("data.dat", "w+b");fwrite(&a[0], sizeof(int), 1, fp);for (i=1; i<6; i++){ fseek(fp, 0L, 0);fread(&k, sizeof(int), 1, fp);fseek(fp, 0L, 0);a[i] +=k;fwrite(&a[i], sizeof(int), 1, fp);}rewind(fp);fread(&k, sizeof(int), 1, fp);fclose(fp);printf("%d\n", k);}程序的运行结果是

A. 21
B. 6
C. 123456
D. 11