[单选]      以下函数为链队列的入队操作，x为要入队的结点的数据域的值，front、rear分别链队列的队头、队尾指针struct node{  ElemType data;struct node *next;};struct node *front，*rear;      voidInQueue(ElemTypex)        {            structnode*p;            p=(structnode*)malloc __(1)__;                   p->data=x;                            p->next=NULL;                               __(2)__;                                    rear=__(3)__;                                       }