在一个带头结点且头指针为head的非空双向循环双链表中,删除尾结点的操作是_______。
A. p=head -> prior;p -> prior->next=head;head ->next=p -> prior;free(p);
B. p=head -> prior;p -> prior->next=head;head->prior=p -> prior;free(p);
C. p=head -> prior;head->prior=p -> prior;p -> prior->next=head->next;free(p);
D. p=head -> prior;p -> prior->next=head;head->prior->next=p -> prior;free(p);