What is the space complexity of the following dynamic programming implementation of the balanced partition problem?

#include<stdio.h>
int balanced_partition(int *arr, int len)
{
     int sm = 0, i, j;
     for(i = 0;i < len; i++)
      sm += arr[i];
     if(sm % 2 != 0)
        return 0;
     int ans[sm/2 + 1][len + 1];
     for(i = 0; i <= len; i++)
      ans[0][i] = 1;
     for(i = 1; i <= sm/2; i++)
      ans[i][0] = 0;
     for(i = 1; i <= sm/2; i++)
     {
         for(j = 1;j <= len; j++)
         {
             ans[i][j] = ans[i][j-1];
             if(i >= arr[j - 1])
                ans[i][j] = ans[i][j] || ans[i - arr[j - 1]][j - 1];
         }
     }
     return ans[sm/2][len];
}
int main()
{
     int arr[] = {3, 4, 5, 6, 7, 1}, len = 6;
     int ans = balanced_partition(arr,len);
     if(ans == 0)
       printf("false");
     else
       printf("true");
     return 0;
}

A. O(sum)

B. O(n)

C. O(sum * n)

D. O(sum + n)

Answer: Option C