单项选择题

有以下程序
#inGlude<stdlib.h>
struct NODE
int num;
struct NODE *next;
main()
struct NODE *p,*q,*r;
int sum=0;
p=(struct NODE*)malloc(sizeof(struct NODE));
q=(struct NODE*)malloc(sizeof(struct NODE));
r=(stnlct NODE*)malloc(sizeof(struct NODE));
p->num=1;q->num=2;r->num=3;
p->next=q;q->next;r;r->next=NULL;
sum+=q->next->Num,sum+=p->num;
printf("%d\n",sum);
执行后输出结果是

A.3
B.4
C.5
D.6