[单选题]以下程序的输出结果是()。#include<stdio.h>structst{intx;int*y;}*p;intdt[4]={10,20,30,40};structstaa[4]={50,&dt[0],60,&dt[1],70,&dt[2],80,&dt[3]};main(){p=aa;printf("%d",++p->x);printf("%d",(++p)->x);printf("%d\n",++(*p->y));} A 10 20 20 B 50 60 21 C 51 60 21 D 60 70 31