What will be the output of the following C++ code?

#include <iostream>
   using namespace std;
   int main()
   {
       int a = 10;
       if (a < 10) 
       {
           for (i = 0; i < 10; i++)
              cout << i;
       }
       else 
       {
           cout << i;
       }
       return 0;
   }

a) 0123456789
b) 123456789
c) 0
d) error