以下程序的功能是计算函数F(x,y,z)=(x+y)/(x-y)的值，请选择()填空。main(){floatx,y,z,sum;scanf(“%f%f%f”,&x,&y,&z);sum=f();printf(“sum=%f\n”,sum);}floatf(floata,floatb){floatvalue;value=a/b;returnvalue;}

A. x-y,x+y
B. x+y,x-y
C. z+y,z-y
D. z-y,z+y