单选题 以下程序的运行结果是()#include <stdio.h>void main(){ FILE *fp; int a=3,b=5,x=0,y=0,z; fp=fopen("test.txt","w"); fprintf(fp,"%d\n%d",a,b); fclose(fp); fp=fopen("test.txt","r"); fscanf(fp,"%d%d",&x,&y); z=x+y; printf("%d\n",z); fclose(fp); }