单项选择题

请读程序:  # include<stdio.h>  f(int b[],int n)    int i,r;     r=l;     for(i=0;i<=n;i++)r=r*b[i]; return r;     main()   int x a[]=2,3,4,5,6,7,8,9;    x=f(a,3);    printf ("%d\n",x);    上面程序的输出结果是 ( )

A.720
B.120
C.24
D.6