What is the most important characteristic of a recursive function? What are the three requirements for controlled recursion in C++? A function h is defined mathematically as: h(n) = h(n) + h(n - 2), h(2) = h (1) = h(0) = 1, n > 2. Write a C++ function to implement this relationship as a recursive function with the signature int h (int n) (d) Use of recursion may have implications for usage of space at runtime. Explain how this arises, by discussing what happens when a recursive function is called