Consider the following iterative implementation to find the nth fibonacci number?

int main()
{
    int  n = 10,i;
    if(n == 1)
        printf("0");
    else if(n == 2)
        printf("1");
    else
    {
        int a = 0, b = 1, c;
        for(i = 3; i <= n; i++)
        {
            c = a + b;
            ________;
			________;
        }
        printf("%d",c);
    }
   return 0;
}

Which of the following lines should be added to complete the above code?

A.

   c = b
   b = a

B.

   a = b
   b = c

C.

   b = c
   a = b

D.

   a = b
   b = a

Answer: Option B