What characterizes a recursive function in programming?

A recursive function is characterized by its ability to call itself during execution. This self-referential behavior allows the function to solve complex problems by breaking them down into simpler, smaller instances of the same problem. In many recursive functions, there is a base case that allows the recursion to end, which prevents infinite loops and ensures that the function will eventually return a result.

For example, calculating the factorial of a number can be implemented as a recursive function where the function calls itself with decremented arguments until it reaches the base case (e.g., factorial of 0 is 1). Through recursive calls, the function makes progress toward solving the overall problem.

Although other characteristics of functions, such as parallel execution, modifying global state, or having multiple return values, are relevant in programming, they do not specifically define a recursive function. The key characteristic remains the self-invocation that allows recursion to occur, making option C the correct choice.