题目：设单循环链表中结点的结构为（data, next），且rear是指向非空的带头结点的单循环链表的尾结点的指针。若想删除链表的首元结点，则应执行的操作是（）。
A．s = rear; rear = rear-＞next; free(s);
B．s = rear-＞next; rear-＞next = s-＞next; free(s);
C．s = rear-＞next-＞next; rear = rear-＞next-＞next; free(s);
D．s = rear-＞next-＞next; rear-＞next-＞next = s-＞next; free(s);
