What is the output of the following implementation of Kadane's algorithm?

#include<stdio.h>
int max_num(int a, int b)
{
       if(a > b)
	return a;
       return b;
}
int kadane_algo(int *arr, int len)	
{
       int ans, sum, idx;
       ans =0;
       sum =0;
       for(idx =0; idx < len; idx++)
       {
	     sum = max_num(0,sum + arr[idx]);
	     ans = max_num(sum,ans);
       }
       return ans;
}
int main()
{
      int arr[] = {2, 3, -3, -1, 2, 1, 5, -3}, len = 8;
      int ans = kadane_algo(arr,len);
      printf("%d",ans);
      return 0;
}

A. 6

B. 7

C. 8

D. 9

Answer: Option D