What does the following code do?

#include<stdio.h>
int cnt = 0;
int recursive_search_num(int *arr, int num, int idx, int len)
{
      int cnt = 0;
      if(idx == len)
      return cnt;
      if(arr[idx] == num)
       cnt++;
      return cnt + recursive_search_num(arr, num, idx+1, len);
}
int main()
{
      int arr[8] ={0,0,0,0,3,5,-6,7},num = 0,len = 8;
      int ans = recursive_search_num(arr,num,0,len);
      printf("%d",ans);
      return 0;
}

A. Adds all the indexes of the number 0

B. Finds the first last occurrence of the number 0

C. Counts the number of occurrences of the number 0

D. None of the mentioned

Answer: Option C