已知head是非空单链表的头指针，p结点既不是头结点，也不是尾结点且所有结点都已具有如下形式的结构定义： struct node { int data; struct node *next; }*p, *pr, *head; 若要找到p的前驱结点并将地址保存在pr中，则下面正确的语句序列是

A.pr = head; while(pr-＞next!=p) { pr = pr-＞next; }

B.p = head; pr = head; while(pr-＞next!=p) { pr = pr-＞next; }

C.pr = head; while(pr!=p) { pr = pr-＞next; }

D.p = head; while(p-＞next!=pr) { p = p-＞next; }