Final answer:
The algorithm is difficult to design using the iterative approach because it requires keeping track of multiple variables and conditions.
Step-by-step explanation:
This algorithm is difficult to design using the iterative approach because it requires keeping track of multiple variables and conditions. With recursion, we can break down the problem into smaller subproblems and solve them easily.
For example, when calculating Abo(n/2), we can simply call the Abo() method again with n/2 as the argument. However, with iteration, we need to manually keep track of the values and conditions, which can make the code more complex and error-prone.