下列程序运行的结果为。#include void num(){extern int x,y;int a=15,b=10;x=a-b;y=a+b;}int x,y;void main(){int a=7,b=5;x=a+b;y=a-b;num();printf("%d,%d\n",x,y);}

A. 12,2
B. 5,25