What does recursion involve?

Recursion involves a function calling itself to solve a problem, which is accurately described in the provided choice. This concept is fundamental in programming, where a recursive function typically breaks down a complex problem into smaller subproblems that are easier to solve. Each time the function calls itself, it should be working towards a base case, which is a condition under which the recursion stops and prevents infinite loops.

Through recursion, certain types of problems can be solved more elegantly and with less code than when using iterative approaches. For instance, common applications of recursion include calculations related to factorials, Fibonacci sequences, and traversing data structures like trees and graphs. Each recursive call can bring in new input parameters, allowing the function to process data in a hierarchical manner. Understanding how recursion works is key to mastering many concepts in programming languages, algorithms, and computer science in general.