[单选题]有如下定义：struct st{　int a;　float b;}x[10];FILE *fp;若文

Afor(i=0; i<10; i++) fwrite(x,sizeof(struct st), 1,fp);

Bfwrite(x,10*sizeof(struct st), 1,fp);

Cfwrite(x,sizeof(struct st), 10,fp);

Dfor(i=0; i<10; i++) fwrite(&x[i],sizeof(struct st), 1,fp);