What is the base case in recursion?

• A. A condition under which the function returns without further recursive calls.
• B. An infinite recursion.
• C. A loop with a fixed number of iterations.
• D. A technique to optimize memory.

Answer: (A)

A base case in recursion is the stopping condition that ends the chain of recursive calls and returns a result. It handles the simplest instance directly so the function doesn’t keep calling itself forever. For example, when computing a factorial, you stop when n reaches 0 or 1 and return 1; that single value is then used to build up the final result as the calls unwind. This termination point is what makes recursion workable, because each call moves toward that base case and eventually resolves.

The other ideas don’t fit as the base case: infinite recursion describes the problem you avoid by having a base case, not the stopping rule itself; a loop with a fixed number of iterations is an iterative approach, not a recursive stopping condition; a technique to optimize memory refers to optimizations like tail recursion or memoization, which are about performance, not the termination rule that ends recursion.