Problem 1 [15pt] Consider the following implementation of Fibonacci numbers int fib(int n) i if (n == 0 11 n-1) return 1; else return fib(n-1) +fib (n-2) a) (3pt) Briefly explain why this implementation is not tail recursive. b) (6pt) Give a tail recursive implementation in the C language. You might need to define a helper function. Hint: rewrite the fib function so that it makes only one recursive call (with more parameters) at each induction step. c) (6pt) Give an equivalent loop-based implementation of the same function in the C language