单选题 在双链表中向p所指的结点之前插入一个结点q的操作为___________

A. p->prior=q;q->next=p;p->prior->next=q;q->prior=p->prior

B. q->prior=p->prior;p->next=q;q->next=p;p->prior=q->next

C. q->next=p;p->next=q;q->prior->next=q;q->next=p

D. p->prior->next=q;q->next=p;q->prior=p->prior;p->prior=q