What is the time complexity of the following recursive implementation used to find the largest and the smallest element

[answerhappygod]

#include<stdio.h>
int max_of_two(int a, int b)
{
if(a > b)
return a;
return b;
}
int min_of_two(int a, int b)
{
if(a < b)
return a;
return b;
}
int recursive_max_element(int *arr, int len, int idx)
{
if(idx == len - 1)
return arr[idx];
return max_of_two(arr[idx], recursive_max_element(arr, len, idx + 1));
}
int recursive_min_element(int *arr, int len, int idx)
{
if(idx == len - 1)
return arr[idx];
return min_of_two(arr[idx], recursive_min_element(arr, len, idx + 1));
}
int main()
{
int n = 10, idx = 0, arr[] = {5,2,6,7,8,9,3,-1,1,10};
int max_element = recursive_max_element(arr,n,idx);
int min_element = recursive_min_element(arr,n,idx);
printf("%d %d",max_element,min_element);
return 0;
}
a) O(1)
b) O(n)
c) O(n2)
d) O(n3)