I'm not sure how to program this in C. The difficult part is the recursion. Please help

Code the following functions using NON-RECURSIVE ITERATION and then using RECURSION test them by calling them from a simple interactive main menu with different values; overall you should have one program containing one main and 14 other functions (7 recursive, 7 non-recursive) where the functions are called based on an interactive user menu. Feel free to create any additional functions if needed. For each function write both function PROTOTYPE and DEFINITION for every function You MUST completely document every function following this basic format 2. Function fun2 (n) is defined as follows: 3. Fibonacci(n) - Fibonacci(n-1) + Fibonacci(n-2); Where n is a positive integer n >- 0 and Fibonacci(1) - 1; Fibonacci(e) - 0; 4. The gretest common divisor gcd(x,y) where gcd(x, y) -X, if y-0 otherwise gcd(x, y) = gcd(y, x MOD y), 1f y 0 5. The function Power(a,b), where Power(2,4) -2 * 2 * 2 * '2 6. A function to display (print) that displays all the positive integers that are less than the value of n and divdisable by m, where m