$3\mathrm{.}1$Implement a recursive function that calculates the nth Fibonacci number. The function should take an integer n as input and return the nth Fibonacci number. Provide a detailed explanation of how recursion works in your Fibonacci function. Your explanation should include:

The base cases and how they prevent infinite recursion.

How the recursive calls progress and how the final result is obtained.

The time complexity of your recursive approach and any potential inefficiencies