下列程序的输出结果是（ ）。struct S { int n;int a[20]; };void f(int* a, int n){int i;for (i = 0; i < n - 1; i++)a[i] = a[i] + i;}int main(){int i;struct S s = { 10,{2,3,1,6,8,7,5,4,10,9} };f(s.a, s.n);for (i = 0; i < s.n; i++)printf("%d,", s.a[i]);return 0;}
选项：

A:1,2,3,6,8,7,5,4,10,9,
B:3,4,2,7,9,8,6,5,11,10,
C:2,3,1,6,8,7,5,4,10,9,
D:2,4,3,9,12,12,11,11,18,9,