What is the output of the following code?

#include<stdio.h>
int recursive_sum_of_digits(int n)
{
      if(n == 0)
        return 0;
      return n % 10 + recursive_sum_of_digits(n/10);
}
int main()
{
      int n = 10000;
      int ans = recursive_sum_of_digits(n);
      printf("%d",ans);
      return 0;
}

A. 0

B. 1

C. runtime error

D. -1

Answer: Option B