What is the code for a loop that iterates from the end of a string toward the beginning?

Question

a. string::reverse_iterator i = s.begin()
while ( i != s.end() )
{
cout << *i;
++i;
}
b. string::reverse_iterator i = s.rbegin()
while ( i != s.rend() )
{
cout << *i;
++i;
}
c. string::reverse_iterator i = s.end()
while ( i != s.begin() )
{
cout << *i;
--i;
}
d. string::reverse_iterator i = s.rbegin()
while ( i != s.rend() )
{
cout << *i;
--i;
}

Answer 1

d. string::reverse_iterator i = s.rbegin()
while ( i != s.rend() )
{
cout << *i;
--i;
}