Everything should be in the C++ language

The Fibonacci sequence is a series of integers

0,1,1,2,3,5,8,13,21,34,55,89,......

See the pattern?Each element in the series is the sum of preceding two elements. Here is the recursive formula for calculating nth number of sequence:

{N, if N= 0 or 1

Fib(N)= {Fib(N-2)+Fib(N-1), if N>1

a) Write a recursive version of the function fibonacci.

b) Write a nonrecursive version of the function fibonacci.

c) Write a driver to test your the recrusive and iterative versions of the function fibonacci.

d) Compare the recursive and iterative versions for efficiency.(Use words, not Big-O notation.)

e) Can you think of a way to make the recrusive version more efficent?