下面的程序使用了函数指针,其运行结果是______。#include<stdio.h>#include<math.h>intf1(inta){returna*a;}intf2(inta){returna*a*a;}voidmain(){intx=3,y1,y2,y3,y4;f=f1;y1=(*f)(x);y2=f1(x);f=f2;y3=f(x);y4=f2(x);printf("y1=
A.y1=27, y2=9, y3=9, y4=27 B.y1=9, y2=9, y3=27, y4=27 C.y1=9, y2=27, y3=9, y4=27 D.y1=27, y2=27, y3=9, y4=9