Consider the following recursive implementation of linear search:

#include<stdio.h>
int recursive_search_num(int *arr, int num, int idx, int len)
{
     if(idx == len)
     return -1;
     if(arr[idx] == num)
       return idx;
     return __________;
}
int main()
{
      int arr[5] ={1,3,3,3,5},num=2,len = 5;
      int indx = recursive_search_num(arr,num,0,len);
      printf("Index of %d is %d",num,indx);
      return 0;
}

Which of the following recursive calls should be added to complete the above code?

A. recursive_search_num(arr, num+1, idx, len);

B. recursive_search_num(arr, num, idx, len);

C. recursive_search_num(arr, num, idx+1, len);

D. recursive_search_num(arr, num+1, idx+1, len);

Answer: Option C